If your doing it safely you take the suction pressure and the line temp into consideration to calculate the SUPER HEAT. That should be about 10 degrees F as a start point and subject to change due to DA and temp.

It is also good to have a BIGGY fan on the radiator to get real world conditions, idling is not good for testing typically.

The high pressure will assist in the proper charging and most KITS dont have more than a low pressure gauge. Over charging can cause the safety to pop off or vent.

It is critically important that you dont rush the addition of freon to the compressor. Never turn the can over to allow liquid into the compressor. you can Chill-break the compressor valves doing fatal damage to the compressor. FYI

W DY