Sounds like you need a bit that doesn't have a bearing or other projection at the bottom, so it doesn't interfere with the projection of the tongue.
Take a look here for one with the dimensions you need:
"http://www.eagleamerica.com/product/v139-1712/ea_-_roundover]Roundover - Plunge Roundover Bits - Flat Bottom"
Thanks that is the bit I was looking for. Actually stood the piece on end (with a Jig) and did it that way. Thanks for the link so I can do it easier next time.:moil::sold: