fiber optic front sight

I'd like to add a fiber optic front sight to my Smith and Wesson model 66 revolver but I'm not sure it is possible to do so. My front signt is not pinned, it is a ramp with a red insert. Looks to me like the front sight needs to be removed, a pinned type added then I could use the fiber optic. In the Midway catalogue it shows two types of sights, pinned and a DK. I don't know what that means.

JB