Won't fit. *No riser attachment :-(

Uhhh...you aren't standing the things on end, you know *

Surely, your saw is big enough so you can lay a 4x4 rail flat on the table
and shove it into the blade at an angle. *You know, taper. *Or use a
hatchet.

The cuts are not made on a flat face. They are made across 2 faces.
And so they don't fit under it since it must ride in on the V part of
the timber. When it is stood on that edge, the height is right at 6"
or more, remember I said they are not perfectly flat square stock. A
hatchet works ok when making one end, but making 2 parallel ends is
more challenging!