Correct foot action throughout the golf swing is indicative of a body that is working well. A body that works well will create the opportune space necessary for the arms and the club to get into the slot - the delivery point where the club has virtually no choice but to do the right thing through impact.
Here is what to look for:
As the club gets into the delivery position the outside of the back foot raises up off the ground - it banks in towards the target. The heel should not be coming off the ground at this point. The foot works in this fashion due to the forward, sliding/driving motion in the hips.
At impact the heel should start to roll off the ground due to the fact that the hips have driven just about as far forward as they can and now they have started to rotate. It is this rotation, and only this rotation, that gets the heel to begin ascending.
Into the finish the foot is fully rolled up onto the toe due to the hips having fully rotated to the target. Because the hips drive to the target to start the downswing and rotate to the target to finish the swing the heel on the back foot will never move away from the target.
Here is a very good drill to give any golfer a greater awareness of what the feet are doing throughout the swing. This drill will not only improve your footwork, but also improve how you shift and transfer your weight throughout the swing.
If executed correctly the finish should look like this with the bottle still standing due to the proper "bank and roll" action of the back foot.
If the hips spin too much and the weight is not driven to the front side enough then the finish will look like this. Notice the contrast between where the weight is in this picture relative to the one above. When the hips are spinning, they have a hard time moving laterally.
Here is additional information on foot action in the golf swing: