Beatles Bible has an intense discussion of how George Harrison (backed by Paul McCartney and John Lennon) played the iconic opening chord from 'A Hard Day's Knight':
The fingering, as played by Harrison on his 12-string Rickenbacker 360/12 guitar, was as follows:
The 12-string guitar was crucial to the power of the chord, giving it a richness which would otherwise have been absent. The notes were also used for the arpeggio at the end of the song.
As Harrison pointed out, his 12-string wasn't the only instrument to be heard during the chord. John Lennon also performed an Fadd9, although on a Gibson J-160 6-string acoustic guitar. Close listening reveals a cymbal and snare drum buried in the mix, and notes performed on the bass and piano.
Paul McCartney added a D note, played on the 12th fret of the D string on his Hofner violin bass. This note was the equivalent of an open D string on a six-string guitar, which had a crucial effect on the overall sound of the chord. The bass note also resonated in the body of Lennon's acoustic guitar, further changing the sound.
(via Making Light)