Why not find some aluminum right angle metal to bolt to the bottom. It should hide the damaged area and prevent any further damaga. And you could always paint it white to match. 3/4" on each side of the right angle should work. Of course, I'm no Phet, but that's what I would do if it bothered me.
Matrix beat me to it. The aluminum gives it a nice defiined edge and protects against additional damage. When plywood is left down on concreate there is inevitably chipping and delaminating that occurs. The aluminum stops that.
ken

