Cite: to reference something and identify that source, especially in academic and legal papers
The lawyer decided to cite John’s affidavit but not Mary’s.
Site: a location or area
They had to clear the site before they could build on it.
Sight: being able to see; what is seen
She lost her sight after staring at the eclipse.
“What a sight!” said the hikers when they reached the mountain top.
The word cite is used less often in general conversations and probably doesn’t suit most business documents. But I do see site and sight being misused.
Think of site as a place where you can sit and it may help you remember which is which.