When a 12 point 1NT is doubled and partner passes, use RDBL to say SOS (Help!!!).

If the Opps decline to bid still, partner should now bid lowest ranked suits up the line to achieve a fit (even if 3 / 4 fit).

If partner actually has 8+ points (you have the balance), they can now pass the RDBL and hope to make a huge score!

It is normally advised that if you DBL 1NT, keep doubling!  In this case, partner panics (correctly) and bids ♠.  How can you not go to game now the evil DBL you planned has been wriggled.....