You could also buy Printfile sleeves that have a pocket for the contact sheet (that's what I do). The ones in the link have 3 holes, but when I lived in Europe the ones I bought there always had 4 (or the 2-hole/3-hole/4-hole universal strip).
There are adjustable hole punches that let you control the number of holes. I have one that I used to punch holes for registration purposes. Do a search online and you should be able to find one.