Transfer Custom fields from ECC

HI,

I am working in SRM 7.0, Backend ECC EHP4. I am working on External requirement. i.e. CPPR

I have some custom fields in ECC PR..i want to create a RFx directly..

I want to transfer the custom field i.e available from PR to RFx in SAP SRM..

How can achieve this???  For CPPR is there any specific configuration need to be done???

Thank you..