F# add9/F
The F# add9 chord consists of the F# (Perfect unison), A# (Major third), C# (Perfect fifth) and G# (Major ninth) notes, with F as the bass note.

How to play the F# add9/F chord
- Play F as the lowest bass note in the left hand
- Find F# (Root) on the piano keyboard
- Add A# (Major third) — 4 semitones above F#
- Add C# (Perfect fifth) — 7 semitones above F#
- Add G# (Major ninth) — 14 semitones above F#
- Press all 5 notes simultaneously to sound the F# add9/F chord