From various boards:

"I had to make big vats of ranch dressing when I worked at mazzio's pizza I had to use a big jar of Mayonnaise, buttermilk, and a big packet that had the ranch spices and herbs in it, and mix it."

"Mazzios in town makes some of the best homemade ranch dressing and they use sourcream, mayo, and a little bit of buttermilk and their own seasonings."

I could not find any mention of what this spice packet contained or who manufactured it. You could probably call the restaurant and find out.