Picture frame rabbets are crucial for fitting art. They're the inner edge of the frame moulding. Determining how deep the artwork sits. Artists must check rabbet dimensions for proper installation, especially with floater frames. The rabbet height equals the moulding's depth. This dimension ensures artwork fits snugly without slipping. Measure the rabbet carefully to match the frame's depth with the artwork's thickness. Correct rabbet size guarantees a secure, visually appealing display of the art piece.