HP Deskjet 6940 - Manual (Page 131)

Follow these steps to set the paper size:
1.
Remove the lower tray from the base.
2. Slide the paper-width guide until the arrow is even with the correct setting.
1 Align the arrows
Note To print on legal-sized paper, set the paper-width guide to LTR.
3. Set the paper-width fence by carefully inserting it into the appropriate slots.
User's guide 129