Which is the proper orientation for a plastic compression ring?
Large end towards the outlet pipe or into the compression nut?

The flat(large end) at the compression nut, the bevelled(narrow end) into the body of the fitting.

the flat(large end) at the compression nut, the bevelled(narrow end) into the body of the fitting.

Thanks for your help. The line is connected now and DRY !

Glad you got it done leak free. Good job.