Errr.....
Ok, let's start again.
1. You can't stitch images if you've got a full frame camera and you've got the Samyang 8mm with the lens hood attached.
2. No, don't position the rig so you have two verticals, both AWAY from the lens and close to each other (but still far apart)....
Here's a good tutorial showing you what to do:
http://www.johnhpanos.com/epcalib.htm
It even refers to setting the R1. Pay close attention to item 4. which shows a piece of tape on a window with a vertical far away being used as the two verticals....