Illustrator :: Put Cut Marks In Document?

I had a leaflet given to me that I agreed to edit. It was A4 in size and fold in three so the original has six faces.  The owner wants to keep the design but reduce it to a single-sheet double sided one third of A4.  So I just did the edits and and made the leaflet into three on a page; like this:
 
My question is how can I put a cut mark in the page.  I am guessing that the leaflets can be cut as required.  Or is that not a good thing to do and should I put them on a standard compliment slip size?