My rabbit used to do this to my Mum when we were kids too - he's just telling you he loves you! I know it's annoying though, and v smelly(!) so maybe castration could be the answer? We had our rabbit "done" and it stopped the spraying, and also made him that little bit more docile.
I had the same problem with my rabbit. If I went outside to stroke him he sprayed me. He didn't do it to anyone else. The vet said it was a sign of affection. Only way to cure him was to have him castrated. It worked and he was still as affectionate but without the spraying.