This workaround worked.  I entered the description in Box H of the Schedule 1 Line 36 smart worksheet as "Form 8903/Form 1099-PATR Box 6" and the return was accepted for efile.  

So prepare the Form 8903 manually to report the amount from Form 1099-PATR Box 6 and save it on your computer somewhere. (I created a special folder called "Proseries PDF Attachments" to park all of these in).  Enter the amount from Form 8903 in Box H of the Schedule 1 Line 36 smart worksheet.  Don't use any description in Box H that has "DPAD" in it.  Attach the Form 8903 to the return before transmitting.