hi,
write a static route to null0 for the nat pool
then enter rip configuration mode, you need to redistribute the static routes. It will be good to use route-maps for permitted announcement
the sample config is:
ip nat pool lan 10.0.0.1 10.0.0.15 netmask 255.255.255.240
ip route 10.0.0.0 255.255.255.240 null0
access-list 5 permit 10.0.0.0 0.0.0.15
route-map subnets permit 10
match ip address 5
set metric 1
router rip
redistribute static route-map subnets
regards,