ADE7953 calibration

I have developed an ADE7953 based energy meter and I'm able to measure RMS voltages and currents. I have yet to calibrate it. I read a document from AD regarding its calibration but I am finding it slightly complicated. There are two methods, using a reference meter or using an accurate source. Can anyone guide me on which method is easier? I do have an accurate source, but cannot control the power factor. Can I use it?