Building on #5, the direct requirements for primary materials of the industries using scrap (based on U.S. use table), like metal and paper production, need to be adjusted based on the country's industry-specific uses of secondary material.
E.g.
Country X uses 30% scrap steel for steel production. The U.S. uses 70% This scrap replaces iron ore (possibly other inputs but simplifying for the example).
If direct requirement for iron ore from U.S. table is 0.1, this can be increased to 0.1*(70/30) = 0.233 to be more appropriate for Country X.