Ensure the view orientation is * Isometric to make sure you select the correct reference point.
Right-click the External Loads folder and select Force .
In the PropertyManager, under Selection:
Click Vertices, Points and select Point1 from the flyout FeatureManager tree.
Select Front Plane from the flyout FeatureManager tree for Face, Edge, Plane for Direction .
Under Unit, select English (IPS).
Under Force:
Click Along Plane Dir 2 .
Type 500 lbf.
Select Reverse direction.
Click PM_OK.gif.