Cite the scanned version of the original dicionary like this:
Toller, T. Northcote, and Joseph Bosworth. "capitol." An Anglo-Saxon Dictionary: Based on the Manuscript Collections of the Late Joseph Bosworth : Supplement. Oxford: Clarendon Press, 1921. 76.
, capitul, es; m; capitula, an; m. A chapter; capitulum :-- Hér onginþ se forma capitul here begins the first chapter, L. Ecg. P. cont. i. 1; Th. ii. 170, 3: iii. 1; Th. ii. 194, 23. On ðam ende ðises capitulan in the end of this chapter, Bt. 32, 2; Fox 116, 33.