Hi Weerakhan,
in case you need to provide a raw material to the subcontractor and get another product back you can create a production model for the subcontracting process in the subcontractor site having as output material the semi-finished product and as component the raw material. Run MRP in the main production site will create stock transfer proposals for the semi-finished part. Running MRP in the subcontracting site then will create production proposals for the semi-finished parts and then also stock transfer proposals for the raw materials to be sourced from the main production site.
Best regards,
Stefan