The inspiration of the name comes from Sir Walter Scott.
In a statement, they wrote: "Sir Walter Scott wrote a legend of King Arthur and his knights laying asleep by their horses in the hollow of the Eildon Hills, waiting to do battle once more. The Greenyards, laying at the foot of the Eildon Hills is where those legends will rise later this year."
Southern Knights head coach Rob Chrystie said everyone at the club is looking forward to the challenge of competing in the Super 6.
He said: “The Southern Knights for 2019-20 is a really dynamic and well balanced squad with some local familiar faces. The management team are determined to create an environment that will challenge all players, while creating a platform for those with the ability and desire to progress into professional rugby.
“This is an exciting time in Scottish rugby and I’m thrilled to be a part of it as we look forward to the inaugural Super 6 season. We can’t wait to get started.”