You need a coil which has a high impedance compared with the circuit you are trying to decouple.
I just had a quick look back through previous posts about this induction heater and cannot see the information we need. (It may be there, I just did not see it).
First, find the impedance of the circuit.
The usual way to do this for an RF transmitter is to divide the amplifier anode/collector voltage by the anode/collector current. ( I include anode for those of us familiar with valves/tubes).
If the voltage is 20 volts and the current is 20 amps, the impedance is 1 Ohm.
So, let us make the impedance of the choke 10 Ohms at the frequency of interest. (10 times the impedance)
As a quick calculation, assuming 60kHz, for a reactance of 10 Ohm, the inductance should be 26uH.
You will also need some decoupling capacitors, again the impedance will need to be low at the operating frequency.
For 0.1 Ohm at 60kHz (one tenth of the collector impedance), we need 26uF. This will need to be low ESR, I suggest several smaller capacitors in parallel, and definitely not electrolytic. Best to use some polyester or whatever plastic film types are available.
Put the decoupling capacitor(s) on the supply side of the choke.
Following audio amplifier practice, the centre point of the collector coil where the supply feeds in would also be decoupled.
But for some reason which I don't know, in RF amplifiers with a push-pull output, the centre point of the anode/collector coil is usually not decoupled with a capacitor. Try both, with and without capacitors at the centre point, and see which works best.
JimB