The utility forward heads to European shores for the first time in his career after enjoying stints with Sharks, Eastern Province Kings, Bulls and Waratahs in his homeland.
Potgieter turned out for South Africa in three Tests in 2012 but has never been able to force his way back into contention with the Springboks.
The 32-year-old will now embark on a new challenge with the Top 14 heavyweights after confirming the move on Twitter.
Potgieter Tweeted: "Very excited to announce that I will be joining @RCTofficiel for the next two years. It's an honor and a privilege to be a part of such a passionate team with so much history."