You would need to trim the bottom of it. They're the same width, but if you look at the 9550 the screen goes all the way to the bottom of the buttons. In fact, the buttons are part of the screen.
Edit: I compared my 9550 to my old 9530, and they are exactly the same width, as I mentioned, but the screen on the 9530 is just a little skinnier to let the screen move around. So depending on how perfectly fitting the screen protector is it might need trimming on your 9530. Nothing a scissors and a steady hand couldn't accomplish though, or a razor blade and ruler, being it will already needs to be trimmed for length.
