Quote Originally Posted by M. A. C. Newsome
I've never seen a vest worn tucked into anything -- kilt or pants. I've also frequently worn various "non-kilt" styles of vests with my kilt and have never had a problem with them being too long. I find that just about most any vest is cut high enough to look good with a kilt.

Aye,
Matt
I'm with Matt....never seen a vest tucked in and when I've worked or gone to black tie events, I've never seen it tucked in either.