When I do this kind of repair, because the original skimmer may not be available any longer I get a 1.5-2mm piece of 316 stainless steal laser cut including the holes as that thickness can produce a nice radiused edge. This first one I did years back was the cut on the laser machine but I opted to drill the holes on site as I didn't know the hole positions, took me ages and a fair number of drill bits it was such tough plate.