Downloading Riverflow 1.0.0 for Mac from the developer's website was possible when we last checked. We cannot confirm if there is a free download of this app available. Riverflow for Mac belongs to System Tools. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. This free software for Mac OS X was originally designed by Katsuma Tanaka.
From the developer:
Riverflow allows you to assign a two-finger gesture to an arbitrary action. For example, a circle gesture can be assigned to send ⌘R key event. Then you can reload the web page by drawing a circle on the trackpad. The app has an easy-to-use interface.
You may want to check out more Mac applications, such as Bulldog, Localghost or Screem, which might be related to Riverflow.