A thin film of grease or oil usually takes care of creaks and such... Now, I am sure someone will come along a say that that stuff on carbon will eat away at whatever and cause your seat to disintegrate and cause you to crash and die, so...

The thing to determine is, is it the rails/clamps? or is it the seat? or is it the seatpost in the frame? You have to isolate each thing too determine the cause of the clicking.