[TxCajun]

Is this problem solved by polishing the feed ramp or by not using flat ammo?

Both, particularly on loading the first round. Pull the slide back and let her rip. Slingshot that sucker.  Is it doing this on subsequent rounds while firing?.  Those flat-nosed rounds can be more problematic feeders, especially in a gun that is not broken in.  It will likely improve but you may have more luck with some round nosed ammo for a while.

Polsihing the feed ramp with some 400 - 800 grit never hurts.  And while you are at it, make sure the gun is properly lubed.
http://goldenloki.com/gunsmith/keltec/lube.htm