Roaming Profiles are used in conjunction with the S9 interface. The S9 interface allows the PCRF to support LTE roaming services such as Voice over LTE. This is done be establishing S9 and Rx sessions between the Home PCRF (H-PCRF) and the Visiting PCRF (V-PCRF).
Roaming Profiles are used to allow or disallow S9 requests at the H-PCRF, and to validate messages coming from the H-PCRF and going to the V-PCRF. A V-PCRF also uses the roaming profile to decide whether to report UE Time zone and location information to the H-PCRF. You can define up to 50 profiles, each with different parameters.