EXCLUSIVE

Kim Richards is great at creating drama on "The Real Housewives of Beverly Hills" -- and even better at creating stories ... TMZ has learned.

If you missed it ... Richards accused fellow cast member Lisa Rinna of hiding a family secret involving her husband Harry Hamlin ﻿-- prompting Lisa to do the whole shout, threaten, and shatter a glass thing the 'Housewives' do so well.

Fans have been speculating wildly about what dirt Kim has on Hamlin -- but we've learned she made the whole thing up just to get under Rinna's skin.

Production sources tell us the issue will be brought up again on the reunion episode -- and Kim will admit she created the whole story.