I have two pictures to describe my situation. In the first picture (attached)second picture, I’ve added red circles where I intend to install vents. I have removed the aluminum capping in one section to expose the wood behind it. I would run the vents along the entire length of the exterior, at what interval, I’m not sure. Between every rafter? Every other rafter?
Here are the vents on your site that caught my eye. I’m not sure if 1/5" is large enough although the exposed wood area in the one picture is roughly 9" high and you’d expect the bottom portion of that to have insulation.