The present disclosure relates to arrangements for attaching an RFID tag to a liquid container, and particularly to a blood components container. The RFID tag may be inserted in an enclosure, such as peel tab, or in a sealed cup attached to a container port. The tag could alternately be embedded in a molded plug or component attached to a port. The RFID antenna could be painted or stamped on the surface of the container. Or the tag could be inserted into the container to float freely in the liquid components. The RFID source may be secured around the neck of a rigid or semi-rigid container, attached with a tether or attached to a connector assembled in association with a blood component or other fluid flow path.