Measure the length and width of the piece of pressboard with a measuring tape.
Transfer the dimensions with pencil marks onto a piece of self-adhesive vinyl veneer, using a measuring tape.
Set a straightedge, such as a level or a metal ruler, alongside the pencil marks. Set a utility knife next to the straightedge and into the veneer. Pull the utility knife through the veneer, using the straightedge as a guide to cut through the veneer. Repeat the process along each of the sides of the veneer.
Place the cut piece of veneer with the protective paper side down, on top of the piece of pressboard to ensure that it fits.
Lift one of the corners of the veneer. Peel away the protective paper on this corner on the back of the veneer. Press this corner of the veneer onto the pressboard, securing it in place
Gradually remove the rest of the protective paper from the back of the veneer, and secure the rest of the veneer to the pressboard.
Set a straightedge, such as the side of a block of wood or a level, on top of the veneer. Slowly pull the straightedge along the surface of the veneer, smoothing it out along the surface of the pressboard.