The part of this towel bar you can't see is probably a half inch or so. You have to be sure that there is a place for the bar to hook onto - you likely cannot hang it on any fake cabinet doors (such as the ones in front of your sink, where you would actually want a towel bar).

You also need to make sure your cabinet door is flat, or the bar may not sit right, and/or it may rub up again and damaged your cabinet's features. The cabinet door probably should be flat for 1 1/2" from the top.

That said, it looks nice.