The front foot is thicker, with a deeper recess.

The rear foot is thinner, with a shallower recess.

If you're reusing the rubber feet, the leftover adhesive should be tacky enough to reuse.

If the leftover adhesive isn't sticky enough or your replacement feet didn't come with adhesive, you can use double-sided tape such as Tesa Tape to secure the feet.

To install a foot, remove its adhesive liner, lay the foot into its matching recess, and press down firmly along the entire length of the foot to secure it.