dropdown option

Hi
I have products that prices change price based on size selected (variable product)

I then have PPOM option (select) to increase the price as a %’age based on what they select in the PPOM dropdown.

However the “(+£0.41)” price is based on the lowest price on the variable product rather than what they’ve actually selected.

For example – if they choose 100mm and the PPOM is set to 10% it’ll show (+£0.10) if however the customer selects 400mm it’ll still show on the dropdown (+£0.10) instead of (+£0.40)

Thanks