The dovetail bit is a 17/32" dia, 7deg angle. If you also need the straight bit, it is a 13/32" dia.
I've only used the original bits that came with my 4212 jig, but have read that the Porter-Cable bits can be hard to find. If so, Whiteside no. RD7531 is the same as the P-C dovetail bit. Hartville Tool has it, for $17.99.