The Scotland striker has bagged 19 Scottish Premiership goals this season - almost half of their league tally.
But his nearest challenger is Rory McKenzie, whose effort in last week’s 2-1 win over Motherwell was just his fourth of the campaign.
With Boyd still to reveal if he will be staying on at Rugby Park next season, Johnston now wants to see the rest of his team taking their fair share of the scoring duties.
He said: “It can’t just be Kris scoring all the goals. Rory McKenzie has done that for us a little bit this season, doing well from that wide role out on the right, using his pace to get in behind teams. He is a real threat when he plays like that and you saw that with his goal against Motherwell last Saturday.
“But we can’t rely on just one player like Kris to score the majority of our goals. It’s great that we have got someone of his quality. However, we need everyone to chip in.
“We do have players capable of scoring goals if they get into the right areas.”
Craig Slater is one such player the manager wants to see troubling St Johnstone keeper Alan Mannus when the teams meet at Rugby Park on Saturday.
He grabbed his opening senior goal against the Steelmen last week - with the help of a mighty bobble which took his low shot away from keeper Gunnar Nielsen - and Johnston says that should be the first of many.
He said: “Craig is more likely to sit in behind the ball and create chances for others with his passing. But he showed he has a goal threat with his strike on Saturday and we will be looking for a few more than them.”