What I feel is the easiest way for someone not used to doing a radius to do would be to first lay out the line with a good water hose.
When the line is laid out then mark off the spacing with marker paint, white works best because the other colors signify utlities. Then I'd paint over the water hose at the space marks. I would make the water hose marks long enough so that after drilling the post holes and the dirt removed I could see the marks clearly. I would set the post using the marks.
Where it gets interesting in radiuses is one glitch of going too far and then having to make an adjustment ruins the whole line. But few things are prettier to see than a properly done radius in a fence line. It's also a great statement about ability and pride.