When back hollowing, use a shallow gouge with a fingernail grind. You
*will* be rubbing the heel (but obviously not the bevel), you want the
wood to be pushing into the edge, not down onto the edge. You will
also be rubbing the tool shaft against the near edge of the opening.

The edge cuts around 45 degrees right of the top (about 1-2 o'clock).

The shaft should contact the opposite edge and the toolrest, so set
the toolrest height about at the centerline. The only purpose of the
toolrest is to keep the tool from rotating down - the contact against
the wood (heel and shaft) does most of the work. The angle of your
bevel will determine where the toolrest ends up.

To start the cut, put the tool on the toolrest, flute down. Contact
the tool shaft against the left side of the wood (so it's wedged
between the toolrest and the wood). Contact the heel next, around
11-12 o'clock, then push the tool in (the heel will move around to
12-1 o'clock) until the edge contacts the wood on the right side.

Or something like that. It's easier to do than describe.