You can usually tell that the female is receptive if she arches her hind legs and hips toward behind her body. I have seen the female do this when the male stamped his feet in the kitchen, The male rabbit will other wise be humping the females tail and completely missing the vagina on the underside. Also the male will have to bite the females hair supposedly in order to get the bunny in the correct position, I know this because the male rabbit in the house right now hasn't gotten the female pregnant so obviously they're doing something wrong. _______________________________________________________________________
The best way I know a breeding took is the buck will mount the doe and do his business, and when he is successful he will roll/fall off sideways and do a strange grunt or sound (the sound is hard to explain, but you'll know it if you hear it). Also, once the buck has fallen off, feel the doe's stomach. It should feel "loose" and squishy instead of how it usually feels.