Alot of people put to much thermal paste on. Just make sure its completely spread-out on the howl surface evenely.
If your using a stock heatsink. Then it will simply snap on, using the plastic block. So very little pressure would be used. But if your using a aftermarket heatsink, then its going to take as much to get the job done as possible. I had to use an extreme amount of pressure to get my aftermarket heatsink in stable.
Finished With TF.