I would like to attach an eyebolt to the ridgeline of my metal roof. I can then attach a rope to that when I need to work on the roof. I am a climber and have the knowledge and gear to secure myself. The rope is mainly to allow me to get up the 10/12 central part of the roof (the ridgeline of which I'll mount the eye-bolt), and not slide off the adjacent 5/12 portions of the roof. It will not be subject to dynamic loading (catching falls); the biggest loads it will sustain are when I haul on it to get up the 10/12 roof (it's impossible otherwise, very slippery).
Since the ridge cap is just a fairly flimsy piece of galvalume, the eyebolt must be secured without reliance on it (and RTV silicon caulked to it). My plan is to drill a hole through the ridge cap, the eyebolt will come through that, and then be attached to the rafters with two u-bolts. Since this is the ridge, it's where the rafters meet. So additionally, I will reinforce the rafters with two triangular shaped steel plates (one on each side of the area where the rafters meet); these will be bolted through the rafter with 2-3 bolts, and then the u-bolts will go through them as well.
This picture shows the detail.