David Foster is reportedly ''getting more serious'' with his rumoured girlfriend Katharine Mcphee.

The 68-year-old record producer has been sparking relationship rumours with the 'Scorpion' actress for several months, and despite keeping their burgeoning romance out of the public eye, sources claim they are now ''really comfortable'' with one another.

An insider told E! News: ''David and Katharine are more serious than they ever have been, and don't care what others around them think. David and Katherine have been spending a lot of time together recently and are not afraid to show affection now.

''David is usually a playboy but Katharine has made him change his ways, and he is really comfortable with her. He tries to fit Katharine into his schedule with dinners and lunches during the week. They both love being out in public together, and are enjoying each other's company. Katharine has always had a crush on David, and she's happy that their relationship is transpiring.''

David and Katharine, 33, were thought to have struck up a romance in October, just five months after David's divorce from wife of four years Yolanda Hadid - whom he split from in 2015 - was finalised.

One insider said at the time: ''It's a little more than casual, but they're not exclusive. Kat thinks they should be a little more serious, but it's mainly casual on his part.''

Whilst another added: ''David Foster and Katharine are hooking up and casually dating on the down low. They are just having fun right now, but they have such a great chemistry and really connect organically on so many levels. There is potential for things to escalate in the future. They were working together and things blossomed as they worked closer with one another.''

When news of their relationship was first reported, it was also claimed the 'American Idol' alum already met David's daughters Sara, 36, and Erin, 35, whom he has with ex-wife Rebecca Dyer.

The first source added: ''She's gone out to dinner with his daughters Erin and Sara. Kat was with them at David's charity event [in Vancouver on Saturday, October 21].''

Whilst the second continued: ''Erin and Sara are particularly fond of Katharine are particularly fond of Katharine and think she is just the most wonderful person. They are totally team McFoster!''