(for example Db major, Eb major, Gb major, Ab major, Bb major).
Rule 1: If there is one flat in the key signature the key is F major
Rule 2: If there is more than one flat in the key signature the second to last flat is the key e.g. Bb Eb Ab = Eb major
Rule 3: To find the key signature (if you have the key) go up to the key note in your rhyme plus one more in the rhyme;
Battle Ends And Down Goes Charles Father.
e.g. Db major= Go up to Db in the rhyme "Battle Ends And Down..." plus one more in the rhyme ... "Goes". So Db major= Bb Eb Ab Db Gb