sniper scope help

i have been making a game and i finally just finished the sniper, but when you look down the scope, its just a hole.
is there any way i can put a sniper reticule down it?
if so, is there a tutorial on it, and yes i have goggled it.

PS. the game is not in blender. im using UDK.

Use an alpha plane with the reticule texture and put it in ‘the hole’.