IBP Purge only one key figure at a planning level

I can not figure out how to purge all the data for just one key figure within a planning level.

For example, say that there are two key figures at planning level MTHPRODCUST, KF1 and KF2. I only want to purge the data for KF1, not KF2 but the Purge Key Figure Data application job only allows you to define the planning level, not the specific key figure.