1999 Questions for all other cars Air Conditioning oil

The manifold came off the back of the compressor and lost all of it's freon charge.

How do I determine if it is necessary to add compressor oil and if so how much?

What is the proper procedure for adding oil to the system so as not to over/under charge it?

Is there a ratio chart available to determine how much there should be relative to the amount of freon charge? For example, the system requires 32 ounces of freon, is there a specific amount of oil that should be in the system?

Thanks