This zip contains six sets of custom crosshairs for Kingpin.
Exract the files to a temp folder somewhere.
First of all make sure you don't have a pak9.pak file in your kingpin/main folder. 
If you want to try all these custom crosshairs copy one into your kingpin/main folder and rename it to pak9.pak
Then start KP and check it out. If you don't like the new crosshairs delete the pak9 file and copy another one into main and rename this one to pak9. Keep going until you find one you like.