Static RP:

ip multicast-routing
ip pim rp-address

int fa0/x
ip pim sparse-mode


Auto-RP
ip multicast-routing distributed

int lo0
ip pim sparse-mode
ip address


ip pim send-rp-announce scope
ip pim send-rp-discovery Scope 16

int fa 0/2
ip pim sparse-mode


Verification:
Show ip pim interface
show ip pim rp
show ip mroute