After less than 10 months of dating, Jim Toth is prepping to put a ring on Reese Witherspoon, multiple insiders tell the new Us Weekly.

"Jim is ready" to propose imminently, says one source.

And the CAA agent, 40, isn't simply going ring-shopping, the source adds: "He's even designing the ring. He wants it to come from him and for it to be completely unique."

Toth also has very specific designs for the proposal itself. "He plans to make it private," a pal says. "[He] will probably take her away or go to her farm in Ojai, California."

And though the actress, 33, is "extra cautious" about remarrying after a painful 2006 divorce from Ryan Phillippe and a 2009 split from boyfriend Jake Gyllenhaal, "she is definitely happy, in love and definitely wants to settle down," with Toth, a pal says.

To read much more about Witherspoon's fast-track romance -- he's "bonded" with her kids Ava and Deacon, how she's "happy to not date an actor" and her ideal wedding plans -- pick up the new Us Weekly, out now.