Fog Radio Access Networks (RAN) refers to the part of the RAN that is virtualized at the very edge of the network, even at the end-user device. Fog RAN support is considered critical for the 5G mobile network architectures currently being developed in various research, standardization and industry forums. Since fog RAN builds on top of virtualization and can involve several virtual functions running on different virtualized resources, Service function chaining (SFC) support for the fog RAN will be critical. This document describes the overall fog RAN approach and also gives some use cases. Finally it proposes some requirements to be considered in the development of the SFC architecture and related protocols.