On the oepning morning in Southport, Knox missed a shortish birdie putt at the eighth to tie for the lead with Poulter before dropping shots at the next two holes then running up a double-bogey 6 at the 16th.
He signed for a four-over-par 74, seven shots more than Poulter while 2016 Scottish Open champion Alex Noren, the other player in the group, had a 68.
“Not very good,” said Knox, who is making his third consecutive appearance in the event, afterwards.
“I could have been under par and definitely level par at the turn and even one-over was still not terrible.
“But I made 6, which was disapppointing, after a poor shot was punished by being plugged in a bunker at the 16th then was unable to make birdie at the par-5 17th with a 7-iron for my second.”
The stuttering start has left Knox facing a third successive missed cut after early exits in both the French Open and Scottish Open in his last two starts.
“It is just not happening,” he added. “Off the tee I was pretty good today but sloppy mid-irons cost three or four shots and that’s a part of my game I’m normally so good at.”
Sandy Lyle, the other Scot out early, opened with a seven-over 77 that included a double-bogey 6 at the 10th.
The 1995 winner started his round in miserable conditons, similar to those when he walked he walked off after just 10 holes in the opening round here nine years ago.