Set up a pair of sawhorses so that you can place the lengths of wood on top of them to provide a comfortable work environment. You must bevel the edges of the siding before they are installed, as you cannot bevel the edges after the pieces have already been installed. Put on all of your safety gear prior to starting.
Adjust the angle of your hand-held router according to the amount of beveled edge you want. Test a scrap piece of wood with varying angles until you find the one that suits your personal tastes. The most common beveled edge is 45 degrees, but you can adjust the head of the machine as you see fit to create larger or smaller angles for the bevel.
Clamp the piece of wood down on top of the sawhorses. Turn on the beveling machine. Grasp it firmly in both hands and push it against the edge of the wood. Walk along the length of the piece of wood siding as you push the tool along the edge, letting the machine cut away the angle you have set with the machine. Repeat the process for any pieces of siding you want to have a beveled edge.