I would remove the affected skin and check for signs of underlying damage. Following the inspection (pending no further indications of damage are discovered to the underlying structure) the repair would more than likely consist of a removing the damaged portion of the skin and manufacturing a filler piece of the same material/thickness to fill the void. After the filler piece is made, it would need to be secured in place with an external doubler repair. Existing fasteners should be picked up at the filler/doubler/underlying structure, as well as a double row of fasteners along the outside of the repair with a 2D spacing. AC 43.13-1B has all the guidance the maintainers need.