There are two options for applying loads to the wedge in Swedge.
The first option is to use a force, which is specified in the input data dialog. The units of force used in Swedge are tonnes. Do not divide the force by the slope face area to get a pressure. Note that the location where the program draws the force is arbitrary and does not represent the exact location of the force. The actual force location is always assumed to go through the centroid of the wedge.
Forces tab of Input Data dialog
The second option is to apply a uniform pressure to the wedge, using the Support>Pressure menu option dialog. The units for pressure are tonnes/m2.
Support Pressure dialog
Both of these options allow you to apply forces that cause a reduction in the normal force on the failure planes. You simply define an orientation of the force in the direction you want.
Whether the load is applied as a force or as a pressure (by dividing the force by the wedge area that the force is being applied to), you should get identical results.