Based on my limited studies and without seeing the score all these chords except the Fmaj fit within the G maj scale. The progressions are
I-IV-I-V
I-V-ii-I
IV-ii-IV-V
I-vi-IV-V
I-vi-IV-V
I am not sure in your example what you mean when you say that F maj sits confortably. Do you mean it follws the G in the second line to give G-C-Am-D-F?
The F chord fits because it is a rootless G7 (try playing it with a G in the bass).
Update
Fmaj of course is not a chord in the G maj scale but it shares two notes with the G maj scale, A and C,
thanks for the reply.
I was just wondering how to use an F here
Makes me feel comfortable stopping.
Is there a technical name for this usage.
I can use this in other songs.
The flat seventh seven… One of the most popular sounds in pop and Jazz, too. Here’s two references – sorry about the formatting. You’ll find many other links on the topic…
“Nowadays the flat-seventh is a fully accepted member of the family of chords that populate the inlands of popular music. That has been quite different in the past. The chord’s rise to acceptance coincides and therefore is often conflated with the successes of the Beatles. Here D. Pinter goes back in time, looking for the flat-seventh in the popular songs of the decade before the Beatles’ hits topped the charts.”