A radio frequency ID tag, very small in size and with an onboard antenna, is manufactured, tested and applied cost-efficiently. The transmit frequency for the tag is set during manufacture approximately, within a selected range, in a gross tuning step. The gross calibration is based on one or more measured characteristics of electronic componentry on wafers, and based on such measured characteristics, the chips can be grossly calibrated and parallel so that all tags will be within a fairly close tolerance of the target transmit frequency. A second tuning step fine tunes each tag by RF communication to set values of capacitance, resistance, etc., and this can be at the point of application of the tags. Other disclosed aspects of the invention also add to economy of producing the tag and reliability of the tags in service.