Arrowheads and Markers

Object vertices, such as lines, poly-lines, ovals, etc., can have arrows and other markers. 

To set or edit the current object marker, use the two marker pop-up menus: the left one controls the start point of an object (Start arrow), and the right one controls end points (End arrow). 

A slider on the bottom of the menu allows you to set the size of the arrowhead.