Closed hook tool or a gouge at right angles to the shaft. Think of it that way and you'll naturally find the way to use it best. Limiting shaving thickness with gentle pressure helps keep even the smallest ring clear on dry wood, but the wet stuff doesn't break, and the long shavings sometimes loop back on themselves. Pencil, or allen wrench in my case seems a good thing to keep handy.
On the subject of larger rings, the stone I got with my original Termite isn't big enough to sharpen the biggest. May not be true now.
I don't hollow with mine, preferring a pointed gouge for that, but it is a great item for cutting smoothly across end grain at the bottom. Fingernail or pointy cut gouge work better on the sides for me.