How to convert .rfa files to .step format.
Converting Revit Family Files directly to STEP 3D Models (.rfa to .step conversion) should be possible, with a small workaround.
You will need to use Revit, and a special plugin you will have to download called OBJ Exporter for Revit. That will allow users to export their Revit files (.rfa) as .obj models. This apparently works only for solid models.
Then all you need to do is to convert .obj to .step, using one of many available conversion tools.
A Revit app for object export
A building design software from Autodesk