The number eight featured in Scotland's brighter moments but knows much more is needed if Andy Robinson's men are to cause an upset against Wales on Saturday.
"We did show that we can create things and if we can finish off then we'll be dangerous," said Johnnie.
"It's disappointing to get off to that start but you've just got to have a 'next game' mentality, look forward to the next challenge and get back on that horse quickly and look to reverse things. It's good that it's only six days away.
"We managed to make breaks in isolation, which was strange. Running in twos or threes next week, with at least one support runner, and we'll finish these things off.
"We'll keep training the way we're training and hopefully bring that back to the pitch next weekend."
Avoiding the mistakes that led to the two French tries will also be crucial.
"They were particularly soft," Johnnie said. "We've got to look to remedy that, remedy the way we're defending around our ruck.
"We talked about that during the week but it's something that we didn't manage to execute the way we wanted to. We can change that moving forward, which is good."
Andy Robinson has added 12 players to the 22-man squad that took on France.
Fit-again co-captain Mike Blair, Euan Murray, Dan Parks, Ruaridh Jackson, Nick De Luca, Jim Hamilton, Dougie Hall, Simon Danielli and Rory Lamont were already part of the Scotland camp.
They have now been joined by Ben Cairns, Scott Gray and Nikki Walker, who missed out on the original selection.
Scotland were also monitoring bruising suffered by Johnnie Beattie (hip), Morrison (leg), Chris Paterson (calf), Thom Evans (calf) and Nathan Hines (calf), and a shoulder strain to Kelly Brown.