IBP Key Figure Calculation Based on Month

Hi Experts

We have a requirement to generate a Key Figure which should be a calculation where based on the month the Key Figure should be populated by either 1 of 2 key figures. For Example the New Key figure Should be populated By key figure one if the month is January and by key figure 2 for months February to December. We know that this is possible for a key figure using the current time period as a reference with the $$PERIODIDnCU$$ operator but can it be done by referenving given monrhs for the calculation

Regards

Ebrahim