Either of these heavy-gauge plated-steel leveller brackets can easily be surface mounted using four screws.
The panel bracket is 1 1/2" wide and 1 3/4" high, and can be reversed, with the clearance hole on the top inside for cabinet adjustment.
The corner bracket has formed ribs and gussets for added strength, and has slotted mounting holes for easy adjustment. 13/16" high, it requires 3" each side from the corner for mounting.
Both are tapped for 3/8-16 threaded leveller feet (not included). Sold in packs of four brackets.