The sign "across" has several
variations depending on your meaning.
The generic sign for "across" uses the "OVER" sign. To do this sign you
use a "flat" hand shape on your dominant hand and slide it across the back of
your (palm down) non-dominant hand.
OVER / ACROSS / AFTER:
ACROSS-FROM (on the opposite side of)
Also see: FINISH
Also see: AFTER