Does anyone know how to use the 'knife' (#6) Speedball lino cutter?

Question:

Does anyone know how to use the 'knife' (#6) Speedball lino cutter?

Maybe I'm not using it right or something. The 'v' and 'u' gouges are pretty self explainitary, but the knife I have not had much luck with. It just makes a small, almost invisible line. Surely I am not using it right. Do I turn it on it's side whilst cutting or what? Anybody that has had experience with this please let me know. Thanks. :)

Best Answer - Chosen by Asker: the knife is to go around all the edges of objects in your picture so that when you make a u or v cut in one object it just ends the cut, and it keeps the edges looking fresh. It's like you are creating a stop line I believe that's what my printmaking teacher called it. It works really well. I loved it, it makes it look more professional. Also it wont show up during printing, I can't imagine a person with a BFA in Printmaking would say that.