The IRS e-file auth form is included automatically when you print a return (Print to PDF) or you can also select "Partial print to PDF" under the Print menu which shows you all forms, just select 8879 which is the auth form you are referring to.

BTW the Print option also allows you to "Mark SSN and add watermark" which I use for my personal copies to ensure nobody else can see my SSN when I share the return with them.

Hope it works for you. Happy New Year!