Holes for the skillet? If the ring is 7" diameter, the radius for the bolts would need to be something greater than. It would also depend on what size bolt with what size diameter head? If you get the bolts too close to the ring then you will need to shave one side of the bolts head, a flat spot.
Measure twice, drill once, is the golden rule.
Also the skillet's height is adjustable but I believe it can be as high as having a 1" + gap above the ring, down all the way, touching it. If you use longer bolts then you can have a greater gap, but too tall and you might encounter problems removing the skillet without hitting the water pan.
Edited by cmayna - 2/15/14 at 8:15am