If you are the preparer and are the third party designee, just check box by entering a 1 to Allow discussion. That is all you do, then at the bottom of 1040, it will check the box to allow IRS to discuss with you. You do not need a PIN. In that same section you decide if you want your name to print (or not). The printed name satisfies the signature requirement for the preparer for filing.  The PIN is at the bottom and that is ONLY IF you fill in the other information for that third party.