NEVER use silicone for anything on the RV!
The frameless window sounds like it has a hinge at the top? You will see some extra metal above the glass, and that is the hinge, which looks more like two "J" shaped fitted together which can move like a hinge.
There should be two tiny screws on top of this metal and their purpose is to keep the hinge from sliding right or left. Unscrew one of these, open the window, undo the crank from the window glass(I have no idea how to do this) and slide the window out. Then you will be able to re-do the sealing gasket properly by removing the old and putting in the new. Maybe, maybe you can get some cheap window rubber strips at homedepot that will work, but it might be too thick, even the 1/4 inch stuff, which is not that tacky either, or the RV store might have exactly what you need.
* On mine the crank mechanism is riveted to the window frame. You will need to drill out these rivets to get the crank mechanism off to get the window free. Use a drill bit about the same size, or just smaller, than the rivet head and once you drill down to the frame the rivet head will be gone and you can use a nail or punch to push the rest of the rivet out. The rivets expand a little when installed so it will take just a small amount of pressure to motivate it out, but not so much you need to hammer.
If you can use small screws to reinstall it, great, but new rivets will never come loose.