Hello,
1) Can you tell me, what device do you use as a RFID reader? If it's supported by Kaa, you can install SDK on it directly. If not, you can use other board with Kaa on it as gateway.
2) You should write a Kaa application which will send events from RFID reader board and an Android or iOS application (using appropriate SDK) which will receive these events.
Write here if you'll have any questions.
Best regards, Taras