Relaying is not needed in your case since the DHCP server is already connected to the networks it will be providing leases to and , I assume,IP routing is enabled. (remember that both network interfaces must have static IP addresses assigned that are correct for the subnet they connect to. If this is not done then the DHCP service will not bind to that interface.)
Look here for details :
If your router doesn't support bootp relaying then you will need to install the DHCP relay agent on a server that is connected to that subnet. The dhcp relay agent will "proxy" DHCP request to the DHCP server on the other side of the router.
Look here for details:
DHCP RELAY AGENT
BASIC DHCP RELAY AGENT INFO
Ferengi Rules of Acquistion:
Rule # 47 Don't trust a man wearing a better suit than your own.