If your transceiver is one of the few which doesn't match offset to sidetone, the circuit is still applicable. However, the offset must first be determined, then R2 adjusted accordingly. R1 - value depends on DC voltage available. The 567 is a common, inexpensive IC and available from any outlet stocking a general supply of IC's. Use tantalum capacitors for stability.
Audio input comes from the transceiver speaker line.
The DC source is usually from an accessory voltage jack on the transceiver. The value of the series resistor will depend on voltage available. Be sure to provide a ground return for the DC and Audio inputs.