Just received this backup sight, but it came without directions of any kind.  Obviously I can move it left or right with the big knob on the right.  Any advice on proper use of this sight?

There is not much to know.  Mount it as far to the rear on your flattop receiver as you can.  You are correct that the knob makes windage adjustments.  Elevation adjustments are made with the FRONT sight.  How much the impact moves per click depends on your sight radius.  Short M4 barrels move more than longer A2 20" barrels.  That is about all that there is to know.  Watch-Six

The small aperature is usefull to help you get it sighted in at 50yds with pinpoint accuracy.  Removing the insert gives you a fast efficient backup iron.  Put the insert for the aperature in a safe place after you sight it in and leave it off the rifle or it will fall out and you will lose it.  You need a backup sight like that to be FAST so you wont need the small insert anyway.  If you think you will need it in the field dont have it stuck in the sight, put it in a platic baggie and keep it on you.

Thanks for the good info, particularly regarding the sight insert.  Now, anyone have any experience with the Knight's flip up forward sight?  Don't have one yet, but am planning on it.