[thejeff]

Same as casting any ritual monthy. 'M', select the spell.

It's flawed, but still useful. It doesn't take into account other search spells cast in the same turn, so if you try to have more than one mage casting it monthly, they'll choose the same province.

It's generally safe to have one mage casting each search spell.
There are a couple of threads here complaining about various other flaws with the automated site search. Hopefully an early patch will address them.