Yes, it's the Squint-eyed Southerner. For bonus again (and since you said you were guessing) - as the Witch King himself apparently (from Gandalf's report at the Council of Elrond) wasn't involved in the attack at the Prancing Pony, where are we told that he and the SqS had met before?
Anyway, correct answer is Barliman - Bill Ferny - Squint-eyed Southerner - Witch King - Glorfindel, so take the thread!
