HSA Remittance to the employee bank acct

We are setting up HSA (Health Spending Account) plans for the first time. The plans have been configured and everything seems to be working, but we have a question as to how the money deducted from each employee gets into his HSA bank account. We had thought we would set up the bank account and deduction amount on an infotype 9, but this merely splits his net amount instead of transferring the actual deducted HSA amt from the wage type.

How are other companies remitting HSA into the various bank accounts?

Thru 3rd party? (If so, how does the bank know how much money to put in which account?)

Or does HSA get remitted via an actual ACH file, like the net payments? (If so, what's the process--RFFOUS_T or a custom exit?)

Thanks for your help!