HOW DO THE LTT RDO IRON SIGHTS CO-WITNESS WITH OPTICS?

With pistol optics, your co-witness depends largely on the optic you're using due to different heights and FOV sizes. For RMR or Holosun 507c, your co-witness will be slightly higher than lower 1/3rd.
For SRO your co-witness will be slightly higher than lower 1/4th. 509T, EPS, and ACRO/MPS co-witness will be about a lower 1/3 and could be slightly lower for the 509T on HK's. 

Please note: For slides with a built-in front sight (92F, 92FS, M9, etc.), we cannot mill a dovetail or install a taller co-witness front sight, as the slide is not thick enough over the barrel.