In Order to Mint to the Rarible|Testnet under you will need some testnet ETH token.  Make sure you have installed Metamask extension.

Step 2: Start uploading your NFT

Enter the Name of Your Token, then a short description, finally choose your file you want to upload to Rarible|Testnet and click Submit

Step 3: You will see your nft link on rarible … click it!  

Once you click the link, you can share your NFT via several social media sites especially SFUN. 

SFUN NFT Rarible Minter
SFUN NFT Rarible Minter – Pics – Rinkeby Testnet|ETH