it sounds like my experiences have been a bit different from helibrewer. i think that some fining agents might indeed take out so much yeast that carbonation is a problem. super-kleer in particular seems like it has a pretty reasonable chance of doing so.
my experience with gelatin has been that if i bottle within about 3 days of adding the fining agent, the beer carbs up fine in a couple or few weeks. but if i go to a week or more, it takes eons to carb, if it does at all.
you can play it safe by adding about 1/8 tsp of rehydrated dry yeast at bottling time.