No, no.
Strike with the ring and pinky-finger knuckles.
I've heard of many punching with those knuckles.. or maybe 3 knuckles. Those 2 and the big one.
But I also just read this comment online.. As an argument to use the first 2. (i.e. not ring and pinky)
"
The alignment of the bones of the knuckles and the hand and wrist are
straighter when you strike with the first two knuckles. The knuckle is a joint
formed by the metacarpals and proximal phalanges. This joint called the
metacarpal-phalangeal joint (MCP joint) is larger and stronger in the first two
knuckles. These are the best anatomic reasons to strike with these two joints.
You should know that there is a specific fracture called a Boxer's fracture
which results when you strike with your last knuckle, either by rolling your
punch from the stronger first two knuckles to the last ones or by direct blow
to the last or 5th MCP joint. These fractures most often occur in fist
fights or when one punches the wall in frustration with your bare hands and
poor technique. When you wear boxing gloves, the distribution of impact to the
other MCP joints and phalanges reduces the chance of fracture. I would not
medically recommend, however, that you strike or roll your punch onto the
weaker joints."