I know its a bit late for the question, but may help others.
This is a schematic of Rick's relay harness.
The open circles are ring terminal connectors.
The solid circles are soldered splices.
^This is one of the major differences between Rick's design and others. Most others use two breakers or fuses, and no splices.
How it works.
The plug into the original headlight socket gets power from the original headlight circuit.
>When power is present in the low beam wire, the low beam relay closes.
>> When the relay closes, that means internally a heavy duty switch connects the heavy wire from the battery and alternator to the heavy wire to the headlight low beam.
High beam works the same way.