I wouldn't use Rita, but I do like it. It's sassy. I think Rita manages to remain uncommon while dovetailing nicely with the trends that are pushing names like Ava and Ruby toward the top. As sibs, I like Rita and Jethro, but Rita and Rivers isn't working for me. TBH, I don't like Jethro and Rivers in the same sibset, either.
My favorite from your combos is Rita Hollis.