I'm transcribing "Can't help falling in love" in D major. The first chord is D major and the second chord is F#m.
I know F# is the third note from the tonic. So harmonized it would be the iii chord; however, instead of the F# immediately above D, I want to play the F# below D (a minor 6th interval). What chord would this be? How would it be notated to distinguish it from the F# chord 'above' D?