NRL referees boss Jared Maxwell said both of bunker official Henry Perenara's decisions were "spot on".

Maxwell told The Canberra Times on Friday the onus was on the attacking team's to execute their plays correctly - with lead runners getting through the defensive line or pass-receivers catching the ball on the outside shoulder of the lead runner.

His comments came after Raiders coach Ricky Stuart said both decisions lacked common sense because the Rabbitohs' defensive line wasn't impeded on either occasion.

Raiders five-eighth Jack Wighton thought he'd scored twice inside the final six minutes of the Green Machine's 34-20 loss to the Rabbitohs at Canberra Stadium on Thursday night.

But the bunker disallowed both of them and killed off Canberra's chances of sending the game into extra time.

First Raiders prop Emre Guler was penalised for stopping in the defensive line, with Souths veteran Benji Marshall making the most of Guler's presence.

Then Corey Harawira-Naera slipped over, with Wighton then running behind the second-rower.

Neither Raiders player impeded the Souths defenders in either instance.

But Maxwell said that didn't matter.

"The bunker decisions are pretty much spot on in regards to how we interpret two different aspects [of obstruction]," he said.

"We've had over a number of years different interpretations around this and one thing I'm comfortable with the current interpretation and how it was applied last night is it's consistent.

"We've been through applied discretion and one thing discretion gives is incredible amounts of inconsistency.

"Don't put it back on the officials to determine the impact.

"Get the play right and if you catch it on the outside of the lead runner then we can determine the significance of it ... then they can make an assessment on what the defender has done - whether the contact's inconsequential or whether it's on the outside shoulder."

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Stuart felt both decisions were wrong and lacked common sense.

"It was smart by Marshall to run forward and try and tackle a person that was going to help him get a penalty, good gamesmanship," he said.

"There was no way in the world they were going to tackle either of those players there.

"Anyone with a bit of common sense in regards to rugby league knows that they were two tries, but I'll leave it at that.

"[Those] type of interpretations in the game it's going to be a blight on the game as well, we've been talking about it for years.

"You can't run forward and tackle somebody in front of you and not try and tackle the person with the football can you?"

The Raiders were sweating on scans for George Williams (hamstring) and Sebastian Kris (ankle) to determine how long the pair would be out for.

Williams injured himself in the warm-up before the Souths loss, but it's believed to be a minor strain and he could play Newcastle at Wagga Wagga next Saturday.

Kris suffered an ankle sydesmosis injury with scans to determine how many games he'll miss. Josh Hodgson could return from a calf injury.