AC Recharge on '96 SC1

[SuperZook]

I am going to recharge the AC on my '96 SC1 tonight. I bought a can of coolant and the kit with the hose. From what I understand, I connect to the low pressure port using the hose in the kit and the can of coolant. I turn on the AC system and let it suck out the coolant. Is there anything more to this process? I know to avoid connecting to the High pressure port and have already identified the low pressure port, so that won't be an issue. How do I know the can is empty? Just pick it up and weigh it in my hand? Any tips on doing the recharge would be helpful.