"Lovers Like Us," a slight but attractively made romantic comedy co-starring Yves Montand and Catherine Deneuve, was known in France as "Le Sauvage."

Montand's character is the exquisitely civilized "savage," a successful, resourceful inventor-businessman, world-famous as a perfumer and the meal ticket of a giant cosmetics coporation, who has gone AWOL on a Venezuelan island, where he lives alone, grows his own food in lush profusion and peacefully tinkers around.

During a visit to the mainland city of La Guaria chance involves him with a disruptive influence - Deneuve as a clumsy, impetuous beauty fleeing from marriage.

The spirit of the entertainment which opens today at the Key, might best be served by the titles like "The Hermit and the Hoyden" or "The Recluse and the Klutz," Jean-Paul Rappeneau is a deft, graceful director. His expert comedy timing and fluid, pretty sense of composition never really fail him, but the script is deficient even on its own frothy terms. Montand and Deneuve seem made for each other only to the extent that each is undeniably and pleasurably a star. It's not as easy to string along with the necessary illusion that the characters they play are an impeccably right match.

Deneuve's character barely exists beyond her impulse to run away and her propensity for creating havoc. The filmmakers find time to reveal a great deal about where Montand has been and what he has done. Indeed, he plays a man of such vast curiosity and skill that each fresh view of his island retreat tends to uncover a new talent or clever, time-saving invention.

The cleverest idea in the script is that Montand is being subsidized without his knowledge. A detective hired by his company has traced Montand to his island paradise. She keeps tabs on his activities and pays handsome bonuses to the mainland people he deals with for supplying information. Hoping that he'll tire of tropical seclusion and eventually return to work, his company prefers to tolerate his defection as long as it doesn't cost them too much money for too long.

There might be more urgency in the romance if Rappeneau and his collaborators had thought of making the heroine the detective. As it is, they fail to characterize her as much more than a beautiful nuisance. If she has a past, a few interesting thoughts in her head or amusing reasons for acting impulsively, she has no opportunity to ingratiate herself by rationalizing her behavior. Provoking mayhem and breaking things aren't all that enchanting for their own sake. Like all the screwball heroines from Carole Lombard to Diane Keaton, Deneuve needs a chance to articulate the inherent lovability of her particular screw-ball.

Good-natured and fast-moving, "Lovers Like Us" is easy to take. One simply wishes the filmmakers valued their resources more. Not much - much enough to fabricate a lightweight entertainment that wasn't so easy to neglect or forget.

The settings are lovely, and casting includes some nice surprises, including American actor Tony Roberts, who costarred with Keaton and Woody Allen in both "Annie Hall" and "Play It Again, Sam," doing a bilingual role. Luigi Vannucchi and Bobo Lewis are equally enjoyable in supporting roles as Deneuve's frantic Italian suitor and the company sleuth, respectively. A character actress whose name I don't know is brilliant in a brief appearance as the insulted bridegroom's hysterical mother. Her shrieks and fainting spells help to explain why the heroine would have been justified in taking off, but it would still be preferable to hear the heroine explain herself to the man she has fallen in love with and imposed upon. Like its heroine, "Lovers Like Us" presumes a bit too much on good will and hospitality.