F# sus4/F
The F# sus4 chord consists of the F# (Perfect unison), B (Perfect fourth) and C# (Perfect fifth) notes, with F as the bass note.

How to play the F# sus4/F chord
- Play F as the lowest bass note in the left hand
- Find F# (Root) on the piano keyboard
- Add B (Perfect fourth) — 5 semitones above F#
- Add C# (Perfect fifth) — 7 semitones above F#
- Press all 4 notes simultaneously to sound the F# sus4/F chord