Watch the vi-IV Kicks online guitar lesson by Brad Carlton from Chord Studies: Pedal Tones Vol. 1
This progression is a vi-IV in the key of C. The chords are Am to F, but we're pedaling the A in the bass. This works out because A is the root in Am and the third of the F chord. We start with our standard Am chord, and then move from E to F on the fourth string as well as an octave higher on the E string.