Cite, a verb, means "bring forward" or "quote by way of example, authority, or proof." Site, a noun, is the location of a building or a plot of land. Sight, as a verb, means "to look at"; sight, as a noun, means "thing worth seeing" or "function of seeing."
His professor felt that Steve should cite an authority to reinforce his thesis statement.
The site for the new gym is right on top of the old one.
After one semester, she lost sight of her vow to study.
Did the searchers sight any survivors?