Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "ofer-mete." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 66.
, es ; m. Food in excess, a feast where food is in excess: -- Se ofermete ne befæst ús nǽfre Gode esca nos non commendat Deo, Past. 43, 9; Swt. 316, 19. Ofermettas commessationes, Bd. 4, 25 ; S. 601, 13 note.