To use Superfluid with xDAI chain, you'll need a RPC URL to connect your metamask or application to a xDAI node.
If you want to learn more about xDAI network, such as websocket connections, the full documentation is here: https://www.xdaichain.com/
Easy button coming soon! Until then, you'll need to add this information manually to Metamask. Click the network button at the top and select Custom RPC.