Dreadful Carnage with a ranged attack

[Wiggz]

Dreadful Carnage reads thusly:

Benefit: Whenever you reduce an enemy to 0 or fewer hit points, you can make an Intimidate check to demoralize all enemies within 30 feet as a free action. Enemies that cannot see both you and the enemy you reduced to 0 or fewer hit points are unaffected.

Assuming you meet the prerequisites to get the feat in the first place, is there any reason to think that you couldn't use the feat when reducing an enemy to 0 or fewer hit points with a ranged attack? If not, then would the effect trigger 30' from the archer or 30' from the enemy?

[Byakko]

Hmn, obviously intended to be for melee attacks, but I don't see anything which prevents you from using it on a ranged attack.

Based on the wording, it should be 30' from the user.