4 pin relays for headlights

I am assuming a 4 pin relay because i am figuring thats the way i need to wire it up

School me. This is why i am asking.

I am currently assuming,

Headlamp wire from switch to electro magnet of relay,
Othe side of Electro magnet side of relay to chassis ground.

Battery hot with fuse to contactor side of relay
Headlamp output to other side of contactor side of relay.

I planned on a standard 5 pin socket, but only wiring up 4 wires as i described above.