Player Core
Chapter 7: Spells
Identifying Spells
Source Player Core pg. 301
Sometimes you need to identify a spell, especially if its effects aren't obvious right away. If you notice a spell being cast, and you have that spell in your repertoire or prepared it that day (even if you already cast it), you automatically know what the spell is, including the rank to which it is heightened.
If you want to identify a spell but don't have it prepared or in your repertoire, you must spend an action on your turn attempting to identify it using Recall Knowledge. You typically notice a spell being cast due to its sensory spell manifestations. Identifying long-lasting spells that are already in place requires using Identify Magic instead of Recall Knowledge because you don't have the advantage of watching the spell being cast.
If you want to identify a spell but don't have it prepared or in your repertoire, you must spend an action on your turn attempting to identify it using Recall Knowledge. You typically notice a spell being cast due to its sensory spell manifestations. Identifying long-lasting spells that are already in place requires using Identify Magic instead of Recall Knowledge because you don't have the advantage of watching the spell being cast.