This is off the top of my head, so double check my work.
ip route [vrf name] 0.0.0.0 0.0.0.0 [gateway]
In your internet router you will need to specify the interface for each vrf subnet.
ie ip route 192.168.0.0 255.255.255.0 [vrf 1 IP]
ie ip route 192.168.10.0 255.255.255.0 [vrf 2 IP]
Hope that helps.