[fenbach]

I decided after all to make a square hole, thinking that would be less obvious.  then cut a small thin square of wood to glue into the recess.
it does look better if not quite professional.  the first pic shows the patch beside the square hole, the second the "repair," such as it is. I went over the case with fine steel wool that I dipped in Howard Restore-a-Finish, the put on a coat of no-buff floor wax.
of course, my biggest take-away is to not drill thru the veneer in the first place!