If you want to seal it yourself, don't bother trying to use silicone. It won't stick to the rubber gasket.
I have used Loctite 'The Right Stuff', available at most auto parts stores. It is marketed as a gasket maker. It adheres very well to the rubber gasket, and also to the glass. It is as easy to work with as silicone, and is very strong. It dries much the same black color as the windshield gasket.
Jim & Kate
2016 Creekside 23RKS, 2014 Ram 1500 Eco Diesel
1995 Monaco Dynasty 36', 2005 Honda Pilot