First of all, for events I make my in a half sheet pan, not the thicker 9x13 pan that is suggested. This is certainly the depth to do if I have to cut particular shapes like hearts. Also, I find it is easier to get more neat pieces out of the more shallow pan. Anything that actually cuts into the krispies would be making cleaner cuts if it's been sprayed with PAM.
Second, when the krispies are mixed and laid out in the pan I cover it with plastic wrap and then use something flat to press them as even as possible. I found that if I only use my hands I never get them as smooth as I would like. The plastic wrap keeps them smooth and my meat pounder clean.