Can I touch the same target multiple times with a spell?

[ChainCurse]

Chill Touch
A touch from your hand, which glows with blue energy, disrupts the life force of living creatures. Each touch channels negative energy that deals 1d6 points of damage. The touched creature also takes 1 point of Strength damage unless it makes a successful Fortitude saving throw. You can use this melee touch attack up to one time per level.

If I am LV5, can I touch the same target five times in one turn? Or do I only allow to touch an target once and five target max for one turn? Can I save the left stacks for the next turn?

[wraithstrike]

You can only touch each creature once per round. Any unused touches carry over into your next turn until they are all expended.

[ChainCurse]

wraithstrike wrote:

You can only touch each creature once per round. Any unused touches carry over into your next turn until they are all expended.

Anywhere I can find this rule for reference?

[FAQ finder]

FAQ: a touch attack is a standard action.