Below is the circuit idea for pocket size FM receiver using RF transistors.
The circuit works off a small 4.5 volt battery or 5v USB. The heart of the circuit is the two RF transistors T1 and T2 to detect the Frequency Modulated signals.Coil L1 and the trimmer capacitor form the tuned circuit to tune the FM station. 10K VR controls the volume to the input of the amplifier. LM386 is the low power audio amplifier that works between 4.5 to 12 volts DC. The amplified sound can be heard through the low impedance head phone
If you need more detailed and robust circuit of LM386 amplifier, refer my old post for Audio amplifier using LM386
