Yes, DOORSILL is a Scrabble word!

Letter values in Scrabble US: D 2, O 1, O 1, R 1, S 1, I 1, L 1, L 1.

Is it a valid word?

DOORSILL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the sill of a door; a horizontal piece of wood or stone that forms the bottom of a doorway and offers support when passing through a doorway