DNS Reverse lookup zone

I currently have two sites main site and small site, main site has all servers with static ip addressing and pc’s with dhcp, two vcentre servers communicating via a two watchguard firewalls.  On our pdc we have the following configuration in DNS:

Forward lookup zone

      Msdcs.domain.int
            (pdc info and ip)
            (sdc info and ip)
      
      Domain.int
                  Folder root:
                  NS – pdc
                  NS  - sdc
                  Host – records for subnet 1 (main site subnet)
                  Host – records for subnet 2 (small site subnet)
                  Host – records for vcenters at both sites

            Msdcs
            NS – Our old server that no longer resides on our domain (treating
            this as a separate issue)
            Sites      contains pdc and sdc info
            Tcp      contains pdc and sdc info
            Udp      contains pdc and sdc info
            Domain dns zones      contain pdc and sdc info
            Forest dns zones      contains pdc and sdc info

Reverse Lookup Zones
      Main site reverse ip (which also contains all of our servers, pc’s etc)



At present there are no reverse lookup records for our small site as they are on a different  subnet.  They do not have a server on site and do query the pdc and sdc servers at our main site for DNS.  Do we need a new reverse lookup zone for this as they are recorded in the forward lookup zone.  What effect does it have on the network adding a reverse lookup zone.

Thanks