Sight it in just like you would a single pin housing with the top pin. On sights that do not have an adjustable 2nd pin, OEM manufacturers generally do the R&D and give you a double pointer so it will automatically tell you where your 2nd pin is sighted in at. If you have a sight that does not have a double pointer, you may be able to add a 2nd pointer to it, and set it for your 2nd pin. At that point you will just have to shoot it and see where it hits, and then put the pointer in the correct location. The reason we developed the double pin originally, was to have a "what if pin", or at least that is what I like to call it, for hunting situations. Before with a single pin, you only had one aiming reference and if you could not take the time to dial, holding over or under in the heat of the moment could get difficult. With the 2nd pin, you could have a reasonable aiming reference, so you know where to hold or possibly even have an added pin to aim with. It also comes in handy to get about an extra 10 yards at the max range of your sight to give you added clearance. But the general idea behind it is to have a single pin sight, that doesn't limit you so much for hunting situations.