RiffPatcher is a small self-contained tool that patches Riff Racer with a custom server for online features.
Simply download the latest release, select the ParseOctane.dll file from your installation of Riff Racer, enter the desired server URL, and hit patch.
For those looking to get started, a good server to begin with is the read-only archive of Riff Racer leaderboards at http://riffapi.hobune.stream..
Note that the .NET 7 runtime needs to be present on your PC in order for the patcher to run, and is only compatible with x86-64 systems.