Roll the thermal putty into a ball.

Place the thermal putty where the damaged thermal pad was, making sure it's centered over the component—in this case a memory chip.

Optionally, you can use the flat end of a spudger (or an included applicator) to spread the thermal putty over the surface of the component.

When you reattach the heat sink, you'll compress the thermal putty and it'll spread the ball out.