I purchased a 1/4 inch dowel rod from the hardware store to use for this. Then, I cut shallow holes in the wood legs and in the resin ankles. I pre-measured the holes so the two would line up. I then put a small bit of silicone in the holes, placed small pieces of the dowel in them, and installed the resin piece.
The ankle is supposed to look like it is part of the leg, so I used some Bondo around the edges to smooth it up. Now, the wooden leg and the resin beefy ankle now look they are are one piece.