Saleae provides a compiled download of the open source RFFE analyzer found here: https://github.com/alejmrm/RFFEAnalyzer
You can download the Windows DLLs for the 32-bit and 64-bit versions of the software here: http://downloads.saleae.com/temp/1.2.5+RFFE.zip
This was built for the 1.2.5 Saleae Logic software and should work on future releases.
If you are looking for OSX or Linux versions, please contact support.
To install, simply copy the correct DLL to the analyzers folder, usually located here: C:\Program Files\Saleae LLC\Analyzers
If you have any trouble with it, please contact support. The analyzer itself is open source and not officially supported, but we can still help debug issues.