Radiant barrier at rafters- what do I do at the top?

My loft has a thick layer of insulation between and above the ceiling joists, then a raised floor above this. I use the loft space for storage so it's not a full conversion, but it's a usable space. Trouble is, it's very hot up there in the summer, presumably due to the dark roof tiles absorbing heat from the sun. So I've opted to fit a radiant barrier to the underside of the rafters in the form of the reflective foil/bubble wrap type of material which people have been sticking on their windows recently.

What's unclear to me is what I need to do at the roof ridge, and also at the soffits. I've seen some guides which recommend leaving a gap at the ridge and the soffits to allow air to circulate, but other installs show it stapled to horizontal battens along the top to create a short flat 'ceiling'. Leaving a gap wpuld seem to avoid any condensation issues, bjt presumably would reduce the effectiveness. My roof has soffit vents all the way along on both sides, but I'm not sure if the ridge tiles are vented or not.