KF calculations - Price changes

Hi experts,

we're trying to create a KF calculation that will calculate the projected price based on an initial price and monthly raises in % as shown in the picture.

Projected price (month n) = projected price (month n-1) * (1 + Price change(n))

Does anybody know how to do this in kf calculations? we tried using IBP_LPA and IBP_PERIODSHIFT but anything seems to work.

Any advice is greatly appreciated. Thanks!