I would not recommend added stop leak to the radiator, it might stop the leak, but it may also create other problems in the cooling system and /or heating system. Is it possible that your vehicle is still under the factory powertrain warranty? The radiator would be covered if it is. Please call me direct and have your VIN number ready, I will check to see if the warranty is still valid.
Please do not use stop leak products, you run the risk of clogging other parts of the cooling system. I n my experience stop leak products do not work. You need a new radiator. We can happily install one for you, we're at 643-2559, just across the MM Tunnel in Newport News.