This is how you do it: drag a normal UIView into a view controller.
Select the view you just dropped and go to the Identity Inspector. In the Custom Class section, change the Class and Module values to NHRangeSlider, and viola!. See attached image, hope this helps...it's the same approach for all these controls that claim Storyboard compatibility.
Can you add an example in your demo app?
When I tried to add a UIView in storyboard an change it to be NHRangeSliderView class, it doesn't work. I'm only able to add it programmatically.