What do I do with my dominant female cat over kitten?
This is unusual. It is usually very easy to get any cat to accept a young kitten.
I think time will take care of this. Also, as you may have heard me say hundreds of times in other answers, SO MUCH of what happens with a cat or between two cats is how the human reacts to them. When the older cat intimidates the kitten, do not yell, throw, startle, or even act worried or annoyed. Talk to her in a silly, baby-like, comforting voice saying something like "You silly girl, that kitten isn't going to hurt you." And give the older cat attention at that point, NOT THE KITTEN.
Don't keep them separated anymore than you absolutely have to. Have two people and both cats in one room so each person can play, pet, brush, feed, etc. each cat at the same time. This allows them to have enjoyable experiences in each other's presence.
Becca's "aggression" is really fear. She is the one that needs the most attention, not the kitten. Pay lots of extra attention to her and don't let her see you making such a fuss over the kitten.
Continue rubbing them down with the same cloth and all the other good things you're doing. When she is near the kitten and isn't acting aggressive, praise her, praise her, praise her!! Most of all, don't overreact when things don't go so smoothly and also have patience. It may take a little time, but they will be buddies soon.
Thank you for writing,