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First of all, you have to use some kind of antenna to catch the RFID signal on 134 kHz. You may use air antenna of about 50 windings of wire (0,5 mm diameter) on the suitable holder with dimension of about 20-30 cm diameter (not necessary to be round). Ends of the antenna you may connect to oscilloscope to observe the signal in time domain or to an audio board of computer using some of the SW available on the internet to observe the signal in time or frequency domain.
There are some other possibilities, but this looks for me the easiest.