You can use the SE-Toolkit to add Actor Pins that
represent communication with an external Actor in an
activity diagram.
Procedure
- Right-click on the action, and select from the dropdown
menu .
- In the Add an Actor Pin window, select the
actor using the combo box, and check the radio button for the direction
of the action.

Note: You can click
an action node to add a pin to represent an input or output object.
Use the Features window to specify the direction, In, Out or InOut,
of the pin and the type of object flowing through the pin such as block, type,
or valueType.