Where do I rack if there is no foot spot on the table?

In that case, hopefully there are diamond markers on the head, foot, and side rails; most but not all tables have them. Try to line yourself up, with the center of the rack right at the center foot rail diamond. Put all the balls in the rack, and then move it forward so the top ball is at the intersection of the center foot rail diamond and the 2nd diamond on the closest side rails. Without the diamonds, the concept is still the same, it just requires more guesswork. Lots of people will mark this with a simple black spot using a permanent marker. On old, felt-worn tables, the felt may be bare in that spot, possibly even have a small dimple where the top ball would be.