Perhaps you mean Rapid shot
Instead? Easy mistake if it was.
Normally, a spell-like ability
duplicates a spell and thus takes a specific action to cast, Eldritch blast does not, and so it must be assumed that it takes a standard action, which is the recommended default.
You cannot take an activity which is a standard action and use it as part of a full attack unless specifically allowed. Thus, using the standard assumption
on how eldritch blast is supposed to work, it cannot be used in a full attack, and thus rapid shot cannot be used.
Ninja'd, but I provided links!