Hello Asker,
the RP is part of the SUP.
The SUP is seen as made of RP and SP.
On a Sup 720 there are:
the RP
the SP
at the logical level
at the hardware level there are two sub-modules:
5 2 Supervisor Engine 720 (Active) WS-SUP720-3BXL SAL09222D5X
5 Policy Feature Card 3 WS-F6K-PFC3BXL SAL09222D1X 1.6 Ok
5 MSFC3 Daughterboard WS-SUP720 SAL09232GJY 2.3 Ok
the RP is the MSFC in practice
Hope to help
Giuseppe