As I know, currently there is no method to convert .itm file to .rfa file. 

If you want to use .itm file in Revit, you could prepare a config and load it in Revit after 2016 version. 

http://help.autodesk.com/view/RVT/2016/ENU/?guid=GUID-692C4E68-6A9D-4628-8E73-0C327E5677D4

Hope it helps

jade.l