Withdraw 27 sapphire rings and a stack of cosmic runes. Click on the spell and use it on the first sapphire ring, then wait until the experience drops from the first one to use the spell on the next ring. It is inconvenient that the rings of recoil look the same as sapphire rings, thus there is no way to tell which ones are enchanted without seeing their names. Bank after you have enchanted all 27, and repeat the process.
Rings of recoil are often used in low-level combat situations to augment damage. There is notable usage when players are battling Zulrah to kill his snakelings. Enchanting sapphire rings into rings of recoil can be very profitable as it is a way for players with low Magic to train quickly and usually make money, but the jewellery market on the Grand Exchange can be very volatile, so it is recommended to test out the profit before buying in bulk.