Put the firearm up for sale. Once payment has been received get the buyers information including:
Im assuming your shipping:
Mailing address
PAL Licence #
Once you have such information, you call the CFC and state you wish to transfer the firearm over to the buyer using their information. Once this is done you will receive a reference number which you will then forward to the buyer.
The buyer using the reference number will call the CFC completing the transfer, and the RCMP will forward a registration cert to the buyer.
Then at this time you can ship/deliver the firearm (Non Restricted) to the buyer. Otherwise you will need to get a ATT (Authorization to transport) for restricted for example, take it from your house to the post office and the buyer will need an ATT to get it from the post office to his house. Feed free to correct me if I am wrong, this is what my understanding is, however I have never purchased a restricted yet.
I think you can use the rifle without the physical cert paper so long as you have the reference number or cert number on hand so that it can be verified if required. Im not 100% sure, I would ask to confirm when you make the initial call.