The rhp is necessary and will contain an embedded version of your top level python script. Inside of this top level script you could call
path_to_rhp = Rhino.PlugIns.PlugIn.PathFromName("MyPlugInName")
The rhp is necessary and will contain an embedded version of your top level python script. Inside of this top level script you could call
path_to_rhp = Rhino.PlugIns.PlugIn.PathFromName("MyPlugInName")