make sure steel is soft enough to shape with the file, goal is to bend the round into the general shape of the checkering file. File the end of your steel to whatever your checkering angle is 60° 75° and 90° are common. make teeth by running the steel checkering file in each side, get it glowing then quench it hard.
moved shops and can't find my carbide tools now but here's an old odd lot dembart next to a bad homemade.
the book the final touch is one of the few actually very useful how to books available in gunsmithing