The stainless steel back glass reveal mouldings are installed on the weatherstrip FIRST .. then the weatherstrip is installed on the back glass.

There is no way...NONE...that once the weatherstrip is installed on the glass, that the mouldings can be installed, as the groove cannot be expanded far enough for the mouldings to fit

Most people...in todays world...including some autoglass shops...are unaware of this procedure which is the same for installing the stainless steel windshield reveal mouldings.