[Rdo-list] how could I set netmask in iptables chain?

In a RDO setup, I could get this in my iptables: -A INPUT -s 192.168.164.63/32 -p tcp ...... But I need <ip address>/16 instead. When seeing firewall.pp, I find this is no such a parameter about netmask. So is it possible to set my own netmask?