Just so we are clear- I do not use the 1/16" cutting bit "mill" for my guitars, but the 1/16" carving bit " ballnose" gives me a nice undercut in the slot for my guitars and violin frets respectfully.
Not to say that one could not try the 1/16" mill and smaller V bits will work but i would recommend getting the Conform vector plug in from LHR.
LG