It may be the food. "Lite" foods tend to be rather lower in fat than is optimal for some cats' skin and coats. Also, dry food can slightly dehydrate a cat over the long-term, leading to increased shed and dandruff.
I've noticed a tiny increase in shed and hairballs since switching my cat to canned Innova Lite; when she was on Wellness and Innova regular formula (all canned), she had next to no shed or hairballs (and this cat was the hairball queen on dry food...lousy coat, flaky skin, the whole 9 yards...all of which disappeared on canned food). On the Light food, I see an occasional flake of dandruff, and a little bit more shedding, which I put down to the lower fat content...I've noticed that Innova's Light dry food seems extremely low-fat to me, in smell, feel, and taste, but that's just my personal perception.
Unless there's a specific health condition tht requires feeding a lower-fat diet, you might want to try feeding a higher-fat, lower-carb food without corn, wheat, or soy and see if that helps before trying supplemental oils or shed-stoppers. Just aim for the same daily caloric intake that you're feeding now with the "regular" formula food (the caloric content should be on the bag). Also, adding more moisture in the form of canned food often helps by keeping the cat hydrated (50/50 canned to dry is usually a fair ratio).