So you hook the volt meter to the potentiometer terminals. With this, you keep the voltmeter on the 100/200mV range. *Note* the max current would be to keep the voltage across the potentiometer terminal below 150mv/ range resistance. An example 150mv (0.150v)developed on the 0.001ohm range is 150 amps. Idealy keep it to 100mV per range so 100Amps max.
For connections hook the common to the ground, and the the intended range to the load. Connect you voltmeter to the potentiometer terminal.
Do you have a model number, I do not have any manuals.
I can do a crude drawing, but it will be tomorrow.