I suspect that you might be referring to a reference in one of the chip guides where "RTP" is used as the descriptor for mold. In reality, "RTP" is more of an insert descriptor than it is a mold descriptor.

Here are 4 examples of current USPCC chips, where the inserts are those of RTP and if one were to describe the "mold" of these chips, it would be "plain". However, the inserts (and the look and construction of these chips) are somewhat unique to RTP/GGS/USPCC, that I suspect the chip guide authors may have decided to not name the various insert designs and simply lump them all together as a single mold-type.

Interesting hobby, eh?