The way it's done in wushu circles, the arms are held out straight, as though throwing a level-fist (palm down) punch at shoulder-height, with the knuckles touching. Remember that stepping forward will close the distance somewhat, so if you gauge the distance with curved arms your bow stance will put you in each other's faces.
This is, as I said, only a setup for distancing. Once this is done (with the feet together and standing straight), of course the actual pushing is circular.
[This message has been edited by Steve (edited 02-22-2001).]