KK window screens
If you have casement type windows, then the screens are normally are installed on the inside of the window frame. You should have a recessed lip on the inside trim around the window frame. The screen would rest in that recess.
What I would do would be to measure the location for the screen (width" x height") and also the thickness of the recess. The thickness could be 5/16", 3/8" or 7/16". You want the screen to sit flush in the recess in the wood trim, so keep that in mind.
Once you have your measurements, go to a hardware store or glass shop in your area who make and repair screens. Have them make you up a screen to those specifications, but don't have them install the screen mesh until you test fit the open frame in your window to make sure it fits.