Type R glyphs are a metaphoric language. You can see examples of them next to the elemental ritual variations.
What happens if you are unworthy is totally up to the Outsider, it cannot be predicted...not by me anyway.
If the Vessel or the Binder wishes to resist I would advise them to remove themselves from the circle. Often if an outsider detects your apprehension, they will remove them self from the circle for your safety, but they might not always notice you apprehension.
The fastest and easiest way to end the ritual is to remove yourself from the circle. I don't know of another way to end the ritual, but I'm sure another way could be found.
Currently there are no plans to expand this work, but I hope to update the scans semi-regularly.