The 30-year-old singer is gearing up to make her return with the new track later this month.
And it's been revealed that she worked with the 'Happier' hitmaker, 34, and the 'Head & Heart' star, 26, the latter of whom has co-written tracks for the likes of Little Mix, Dua Lipa, Beyonce and Madonna, on the tune.
A source told The Sun newspaper's Bizarre column: "'Flame' was written a while ago and has great potential.
“It was the natural choice to put forward for the film and works really well in it.”
'Flame' is set to feature in the Sky Cinema movie 'Twist', which is released on January 29.
Rita plays a female version of The Artful Dodger, the juvenile pickpocket gang led by Fagin (Sir Michael Caine) in the remake of the Charles Dickens classic 'Oliver Twist'.
The pop star's last music release was the 2020 single, 'How to Be Lonely', which was passed to her by Lewis Capaldi, who admitted he was "f****** s****" at singing it.
The track only made it to number 57 in the UK Singles Chart.
Meanwhile, Rita previously explained that she wanted to come "come face-to-face" with "a bit of a challenge" on her upcoming third album.
The 'Fifty Shades Freed' actress said fans can expect a totally different experience on her follow-up to 2018's 'Phoenix' and revealed that her desire to experiment came from wanting to push boundaries with her art.
She said: "People have been coming to studio sessions from all over the world.
"I've been working on this now for the past two year on-and-off.
"I have plans for this third album to be something I've never done before and I really want to experiment and come face-to-face with a bit of a challenge.
"So there are writers I've never worked with before and live instrumentation.”