I agree with Joe. I generally use one of the colorul feathers between the fan and the body inside a call.
Place your feather of choice on a soundboard that hasn't been glued into the call to get an idea of the size you need. I like to get as close as I can to the top and bottom of the soundboard, but you may have to manipulate the pointed top edges of the feather a bit to get them to lay right.
Put a tiny dab of goop glue on the back of the feather spine about 1/4" from the tip and lay it on your soundboard. I like to place a small chunk of wood (usually a cutoff from a striker blank about 2" long) above where the glue is on the feather. Generally 30 minutes will allow the glue to dry enough to keep the feather positioned.
Be aware that some CA glues (super glue) will cause a frosted or hazing effect on the underside of your surface glass if you use it to glue the feather in. I learned the hard way.