Configure Fortigate vdom interface for proxy DHCP

We are implementing a new vdom on our Fortigate 1801F (firmware 6.4.6) in a vrf environment (Not the Fortigate vrf solution). In our test setup we have two local vlans (71 &72, 10.71.0.0/24, 10.72.0.0/24). Traffic from the vlans traverses our WAN and uses vrf with routing marks to connect to the Fortigate vdom. Vlan 71 routes through FortiGate vlan 1100 (10.110.0.1) and vlan 72 routes through Fortigate vlan 1101 (10.111.0.1). This is working perfectly. 

To duplicate our L2 vdom solution, we want to configure the Fortigate vdom as a proxy DHCP server (if that is possible). We want vlan 1100 to assign 10.71.0.x addresses to vlan 71  clients and vlan 1101 to assign 10.72.0.x addresses to vlan 72 clients, via L3

Is this possible? Could use a good doc if someone has something to follow.

Thank you for any assistance.