Click the Supports Link button 
on the diagram toolbar.
On the Diagram, click the source element.
Drag the link to the destination element.
Drop when the destination element is highlighted.
A supports relationship represents the relationship a component has to the implemented interfaces, and can only be drawn from a component to an interface.
To create a supports link:
Click the Supports Link button
on the diagram toolbar.
On the Diagram, click the source element.
Drag the link to the destination element.
Drop when the destination element is highlighted.
Related Topics:
Creating Links
Moving Links
Editing Links