From your writing I do not know what is the DC current you will send through its specified DC current or voltage.
Due to the very low frequency limit for AC, 10 kHz, one of the inductors in the bias tee must be of the order of > 100 mH, thus made of a thin wire. The DC current may be limited to < 0.1 A.
On the DC end of the bias tee, the AC component is suppressed by the inductors and capacitors in the tee. If you still feel the DC power supply may be affected by AC, you can simply add a capacitor across the DC port.
You have not mentioned the DC or AC power to be transmitted over your combined line. Again, some limitations may exist in the bias tee.
On the other end of your line, the load should be 50 Ohms to maintain the line matched for RF, but this load may consume the DC power, too. If you do not want the DC to be loaded with 50 Ohms, you can use another bias tee to separate them, or, if DC is not to be used on line end, you can use a simple DC block, or series capacitor, to stop the DC current. The capacitor should be, however, large enough to pass the 10 kHz to the load. Its reactance should be < 10 Ohms at 10 kHz, smaller than 50 Ohms of line impedance.