present it as something fun, not shameful. stress that you enjoy the current sex and don't want to leave it behind. (don't get greedy or neglect her needs. be extra open to those needs or her interests.) give her room to think about it if she needs to, don't disclose and try in the same night unless she initiates. she has a right to say hey, that's not for me but you're not asking for any super weird or sketchy fetish here. if she does decline you get to decide if the relationship is worth never indulging in your kink. overall you could both aim to be good, game, and giving (Google it if you're not familiar.) good luck!