Does an increase of area lead to more collisons in a confined jar of gas? I'm reading a lecture by Richard Feynman in which he is talking about the behaviour of gas molecules/atoms within a confined vessel. 

The confined vessel is a cylinder with a piston to stop the water molecules from flying out. 

However this follow sentence has me stumped

"Clearly, the force is proportional to the area, for if we increase the area but keep the number of molecules per cubic centimeter the same, we increase the number of collisions with the piston in the same proportion as the area was increased."

If the area of the piston is increased, but number molecules remain the same, would there not be less force as the collisons are spread out?

I'm thinking of this in the same vain as shoes exerting less pressure than high-heels due to the increased area.
Pressure is force over an area, or as an equation you might state that as:

$$P=\frac{F}{A}$$

Which can be rearranged as

$$F=P \cdot A$$

You are correct in saying that if the number of molecules are held constant, that the force would be over a larger area and therefore decreased. As you increase the area but keep the number of molecules constant, the pressure decreases proportionally, and no change in force is seen, but what Feynman was talking about was keeping the amount of molecules per cubic centimeter constant, or in other words keeping pressure constant. This way as area is increased, you see a proportional increase in force.