Softlist Material Formulas

Hi, I'm hoping someone can help me get a better grasp on how to create formulas for my materials lists in customizing SoftList. Specifically, I'm currently trying to add Ice & Water Shield to my roofing materials, which is calculated as my hip edges (which I can make by defining Roof Perimeter with "has gutter") plus valleys divided by the linear footage of the roll. I'm struggling with figuring out how to add both the perimeter section and the valley section, as it seems the material list is making me choose between Roof Perimeter and Valley. I'm sure there's probably an obvious answer, but I'm missing it. Thanks!

Update: I've dug enough to set the roof component to "Roof" and made the formula list((perimeter+valley_length)/65) but for the life of me, I can't figure out how to get it to actually calculate and show up in my SoftList.

UPDATED UPDATE: I FIGURED IT OUT. I needed to add it in the layout area and then regenerate. For anyone else trying to do it, I landed on the following formula: list((hip_length+valley_length)/65). Note that the 65 is because our rolls of Ice & Water cover 65 linear feet.