Most non-stick materials can't be used above temperatures above 400 degrees without emitting toxic fumes.
Using cooling racks in a sheet-pan for roasting items in the oven is a common practice in the food industry.
If you are in doubt about the materials, don't use it. Better to err on the safe side.
If you are roasting something like meat, you can use a layer of root vegetables below the meat to lift the meat up off the floor of the pan. Another thing people sometimes use are the burners from a gas stove, just wrap them in foil. You might also consider placing the item directly on the rack of your oven and place a pan under it on the shelf below to catch drippings. If you have a toaster oven, consider using one of the racks from that oven in a sheet pan. If you have some of the Ball lids used for canning, you can fill the floor of a sheet pan with them before placing your item on them.