I am unsure how you could insert an RFID chip into a mass of conductive metal and still have it function. The conductive metal would form a Faraday cage around the chip preventing it from being interrogated.
There would also be the discrepancy between the item's actual weight and chipped weight.
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)