Watch the Thrilling 3 Piece: 6 online guitar lesson by Ben Lacy from Two-Hand Groove Guitar
I use a chord smack to ring out an F chord on the 10th fret. That means I smack up at the 22nd fret.
The timing might be a bit tricky. It's the last 16th-note of the bar, so on the "uh" part of beat 4 - 4-ee-and-UH
Or you can just think of it as right before the downbeat. Either way, be sure to let it ring out.