i disagree with spreading it with a credit card
i suggest putting the grain of rice size dot in the center and then applying your hsf. the pressure of hsf spreads the paste where it needs to be...which is the center of the cpu's heat spreader.
read from the arctic silver5 website under installation, they have a good reason for not spreading it. i.e. the heat transfer is more efficient if the paste is centered on the cpu instead of totally covering it.