Their seem to be only two instances in King's Quest VI that require the
manual, the logic cliffs, and the floor puzzle in the catacombs.

The logic cliff puzzles are cracked so just enter anything.

The riddle for the catacombs is as followed, taken directly from the manual;

Three roses laid upon the bower,
A scythe for he who cuts the flower,
A crown, a dove, most noble race!
Thy bones make sacred this dread place.

Have fun!

Destroyr