In general you drag the fingertip of an index finger
across the bodypart where the scar is located.
In ASL the fingernail (or a thumbnail) is sometimes used to represent a
blade or scalpel.
So, when signing "SCAR" make sure that as you drag the finger such a way
as that the fingernail (if sharpened up) would be cutting the skin.
If you drag the tip of the index finger of an "X" hand it means
Typical usage would include: PRO.3 HAVE SCAR-(location: "right cheek")
This would be interpreted as "He (third person pronoun) has a scar on his right cheek."
Multiple scars in the same area could be shown by dragging a "curved 5" handhape (claw) across the area where there are
SCAR (general and/or on cheek) or "a cut on the cheek" / "it sliced the
SCRATCH (a scratch on the cheek)
Note: If you mean scratch in general, do it on the back of the