First of all, it's usually "Call the Quarters" as Circles do not have corners. :-P
And if I'm doing a small, solitary ritual, I usually just say "By the Earth that is Her Body, the Air that is Her Breath, the Fire that is Her bright Spirit, and the living Waters of Her Womb" as I point to the North, East, South, and West, respectively.
However, with my Circle... We, as a group, are so Eclectic, that we decided that whoever is "in charge" of the Ritual, gets to do the Ritual in (his or) her own way. For instance, last May we had a ritual run by a "Crazy Virgo with CDO (that's OCD, in alphabetical order)" where we did the Quarters...in alphabetical order!!
Whatever works! To each their own!
at 1:30 PM on Oct. 28, 2010