Language / How to properly ask for girlfriend's hand in marriage to Polish speaking parents? [6]

I plan on proposing to my girlfriend in the next few weeks and am planning to ask her parents for permission first (I've seen arguments on whether or not you should, however I am, so please no discussion of that). The way that I understand you say it is "Chciałbym prosić o rękę Państwa córki". Can anyone verify this or offer any alternatives? I know that previous phrase means "I'd like to ask for your daughters hand", however how do you add the "in marriage" part at the end? Thanks!