The former "Smash" star wed music producer David in June and has since adopted a double-barrelled surname which was used to introduce her as she attended the recent Vocal Star seminar for aspiring music professionals.
Speaking to Entertainment Tonight at the event, Katharine was asked why she'd opted to become a McPhee Foster, to which she replied: "I'm a romantic. I've always liked the idea that it's still a traditional thing that exists in our society. I like the idea. I think it's romantic and it's a great last name."
The 35-year-old singer and actress also admitted she hasn't got used to her new moniker yet, laughing: "We've been away since we've been married, so (I'm not used to it) yet, but I love it. I just love the ring of it, so I'm enjoying it."
Following their London wedding, Katharine and David jetted to Italy for their honeymoon. And the pair are still enjoying their newly married status, with the stunning brunette adding: "We just love being with each other. There's no arguing, no drama. It's just easy. That's how it should be."