finding small R in series RLC circuit
A total rewrite is done due the edit in the question and the comments.

The circuit has resonant frequency about 5,3MHz. 30nH is so small inductance that all wires and and other parts can well have as much inductance, so the resonant frequency can be totally different, probably lower. If it's higher, you have some unwanted loading. You must have proper low capacitance high Z measuring probes.

Not asked: Inductance 30nH is practical in bandpass filtering resonant circuits at 100...500MHz. At lower frequencies narrow band filtering effects do not happen due high series loss resistances when compared to the reactance.

If you find the resonant frequency, you can measure the impedance of the circuit by adding a shunt resistor for current measurement. Then simply subtract the shunt resistor and you have the total internal resistance of the circuit, also that which is distributed as a non-ideality in the other parts than the assumed 0,5 Ohm resistor.

Comments suggest omitting L out of the measurements, because the left end of R and the right end of C are available. You obviously want to apply ESR measuring techniques to it.

The idea is acceptable, because then L=30nH is out of the problem. 

ESR can be measured by measuring the impedance at so high frequency that the reactance of the cap do not hide the result. You can for ex. make a bridge and find external RC series circuit which has the same R and C or at least the same RC product. The frequency must be megahertzes to push the reactance down. That makes the circuit difficult - you cannot have long wires, only centimeters. Avoiding leakage needs care.

You can also construct a pulse integrator, where the capacitor is the RC part of your circuit. The initial jump of the output voltage shows ESR. Unfortunately You will need pulses which rise in few nanoseconds to be able to see anything substantial. Pro level pulse circuit design is a must. If there's substantial stray inductance, it will be seen as ringing which can totally hide the wanted result. 

NOTE: helix-type metal film resistors can have too much inductance.