I've been making soda bread almost my entire life.
I knead it a bit, the same way I do my scone dough - not too much or it will get tough.
I form it into a round, slap it onto a baking sheet and cut straight down first one way, then the other all the way to the pan - so it is in 4 quarters but still together. I use a bench knife.
It looks like this. Usually like the one on the left but sometimes like the one on the right.
I've never seen it done any differently.