Which formula are you feeding? To be honest, my complaint with THK is that it often has TOO MUCH fiber, the dog will poop 4-5 times per day and often not digest the veggies very well. Are the poops solid, firm, or sort of loose/falls apart with large chunks of veggies?
Fiber can firm up the poop, yes, but too much and it just pushes everything through. You end up with a large volume but not firm enough to help express the anal glands.
I had the best luck with THK products when I soaked the food overnight (in the fridge) and added a probiotic/digestive enzyme product. When I did that, my sheltie went from pooping copiously and loosely literally every single time he went outside (6 times a day!) to about 3x/day and much smaller, firmer, poops.