Place it with the skin side up and use a very sharp knife to score the skin in a cross-hatch pattern. Take care to only score the skin, don't cut down through the fat also.
Apply a liberal amount of salt on both sides, and then do the same with the rub.
Fire up the grill, prepare it for indirect heat. Try to keep it at 130° C / 265° F. Place a few chunks of wood on the glowing embers for smoke flavor. Place the skin on the grates, skin side up, and close the lid. Smoke it for approximately 2.5-3 hours, it is done when the temp in the fat is 95° C / 203° F.
Now gently remove the skin from the grates.
Shovel the charcoal into a pile, add more if needed. Stoke the fire to get it real hot.
Place the skin, skin side down, back on the grates right above the glowing embers.
Sear the skin side for 30-50 seconds, check it often to see the blisters forming, but without having it turn all black.
Remove the cracklins from the grill and let it cool off for 10 minutes before digging in.