Difficult to tell without a picture... lots of ways to attach fittings to skins. If its a plastic or metal fitting of some kind you could probably rivet it if its quite thick or, if its thin enough, sew it. I make up my own skins from lengths bought off a roll and ususally sew the tip fittings on or by sewing a tab of the skin back on itself (plush to plush) to make a loop for a wire or cord. Or I did until I broke the sewing machine last week and had to rivet one on.
Firstly I've nil knowledge about skins. However for some mending jobs I use one of the widely available flexible adhesives backed up with stainless steel staples from Amazon (ordinary office stapler)......might be of use and easier and? stronger than some hand sewing.
Lorraine McCall began her attempt today at a continuous, self-powered round of the Grahams, a four-month tour of upland Scotland combining walking and bikepacking. If successful, she'll be the first person that we know of to do it.