A range spell that deals d4 as a cantrip isn't out of the question either as long as it is close range since the damage is comparable to a sling. Beyond that though bump to 1st level.
I've updated the first post - Disrupt Undead is a ranged spell that deal 1d6 points of damage to undead as a 0-level spell. My spell is a touch version of the same spell - is 1d8 damage fair (for losing the ability to use the spell at range?). As a comparison, it would be equivalent to a longsword's worth of damage, only against undead.