I think other posters have done a nice job of outlining some sources you could go to. I want to especially echo that another biblical name might be nice with [name]Jonathan[/name]. Additionally, some of the names suggested actually have use by both sexes in the Bible. [name]Noah[/name] spelled [name]Noa[/name] is in there for a female figure, and [name]Micah[/name]/[name]Michael[/name] is in there as a woman, [name]Michal[/name] (I’m not 100% sure the names are eytmologically completely the same, but they’re very close in sound at any rate).
You came here for opinions as well as inspiration, so: If you are going to stick with a very masculine name, let me put aside my own feelings on that and just argue against [name]Richard[/name] specifically for a sec.
I don’t like to put down anyone’s favorite, but I do have what I think are some real considerations about this one.
Here’s the thing about [name]Jonathan[/name]: in addition to [name]Jonnie[/name] now, she also has the option to go by femmier [name]Joni[/name] (a la Ms. [name]Mitchell[/name]) or even, by a stretch, [name]Joan[/name] (perhaps spelled [name]Jon[/name], I don’t know) when she’s older, if she so chooses. I don’t think [name]Richard[/name] gives that option. There’s [name]Richie[/name] and [name]Ricky[/name]/[name]Rickie[/name]/[name]Rikki[/name] etc, and that’s it. I also don’t think it’s going to be an easy name for her in a certain age range when her peers learn that [name]Dick[/name] is a historical nickname for [name]Richard[/name] (I have male friends named [name]Richard[/name], and it was hard enough for them). Finally, I’m not sure [name]Richard[/name] [name]Robertson[/name] is the best sort of alliteration. It’s not the very worst, but it’s just one more strike against it.
Let me propose as an alternate to [name]Richard[/name] a boys name for a girl I think gets both a boyish nickname and a potentially girlier one or two, just like like [name]Jonathan[/name]: [name]Andrew[/name]. Another Biblical name. Nn [name]Drew[/name] is very boyish but actually has some feminine use through Ms. Barrymore, and I think [name]Drew[/name] [name]Marie[/name] has a nice rhythm the way [name]Jonnie[/name] [name]Rose[/name] does (1-2 and 2-1). But there is also the option for another boyish one, [name]Andi[/name]/[name]Andie[/name]/[name]Andy[/name], also a little bit known for girls through Ms. McDowell. [name]Andie[/name] [name]Marie[/name] is fine. AND if she wants to go by something more feminine when she’s older, she can style herself [name]Annie[/name] or [name]Anne[/name] the way [name]Jonathan[/name] might have [name]Joni[/name] or [name]Joan[/name].
[name]Andreas[/name] does something similar if you like it better: [name]Drew[/name] is more of a stretch from it, although you could still do it(I wouldn’t recommend Dre, because of Dr. Dre being such a strong association).
What else: [name]Matthew[/name] could be [name]Matty[/name]/[name]Maddy[/name] which is very in for girls right now, although that’s it as far as nicknames go I think. [name]Maddy[/name] [name]Marie[/name] is kind of cute.
[name]Elliot[/name]/[name]Elijah[/name]/[name]Elias[/name]/[name]Elisha[/name] - anything that could plausibly be [name]Ellie[/name] for a nickname or [name]Elle[/name] ([name]Elle[/name] [name]Marie[/name]!)-- notice this came up in pp’s suggestion too via another route. Again those are only two femm-y nicknames with nothing more boyish, although they are two!
[name]Everett[/name] nn [name]Eve[/name]/[name]Evie[/name]/[name]Ever[/name]: [name]Eve[/name] [name]Marie[/name]!
[name]Evan[/name] nn [name]Eva[/name]/[name]Eve[/name]: [name]Eva[/name] [name]Marie[/name]! Also somewhat known from [name]Evan[/name] [name]Rachel[/name] Woods.
[name]James[/name]: Does have [name]Jamie[/name], and model [name]James[/name] [name]King[/name] makes this faintly familiar.
[name]Dorian[/name]: All-boy, but feels feminine through [name]Dora[/name]
[name]Julian[/name]: All boy, but nn [name]Julie[/name] or [name]Julia[/name] is there. [name]Jules[/name] is kinda either/or. [name]Jules[/name] [name]Marie[/name] is actually really nice for me!
[name]Joseph[/name]: nn [name]Jo[/name] ([name]Jo[/name] [name]Marie[/name]!), [name]Josie[/name], [name]Effie[/name]
[name]Josiah[/name]: see above, minus the [name]Effie[/name]
[name]Lionel[/name]: All-boy, but another way to [name]Ellie[/name] (actually, that’s an option for a lot of boys names with -el, really).
[name]Louis[/name]: All boy, has all of the [name]Lu[/name]/[name]Lou[/name]+ options (Lulette, [name]Lula[/name], etc.) and [name]Lou[/name] [name]Marie[/name] is really cute! [name]Luca[/name]/[name]Lucas[/name]/[name]Luke[/name] gets you sort of the same thing.
[name]Bryce[/name]: Faintly known on girls through Ms. [name]Howard[/name], [name]Bryce[/name] [name]Marie[/name] is really cute. I think it may capture some of what you like of [name]Richard[/name]?
[name]Reese[/name]: Very well known through Ms. Witherspoon, but very boyish and [name]Reese[/name] [name]Marie[/name] is very cute. A lot less name than [name]Jonathan[/name] though. [name]Bryce[/name] has the same issue but a little less so.
[name]Miles[/name]: Nn [name]Mila[/name] or [name]Milly[/name] - [name]Mila[/name] [name]Marie[/name] is pretty cute!
There are more I’m sure!
I hope this helps! All best!