The 19-year-old Northern Ireland Under-21 internationalist has played 19 first-team games, but admits he was not ready for the SPL when he joined from Ipswich last summer.
McKeown is looking to make a bright start to this season against Dundee at Rugby Park tomorrow.
He said: "Before I signed I had only played youth-team games at Ipswich. I came here and it was a bit of a culture shock.
"I was playing against people who were physically stronger and mentally smarter.
"You have to learn and grow up quickly and I think I did that.
"Hopefully that stands me in good stead this season."