How to create a Manual AR Invoice with Multiple Lines

How do I create a manual AR invoice for Intercompany Service Fee Revenue that has the following accounting:  

 

Debit   AR Receivable                                  20,000

Debit   Adjustment for Withholding Tax            2,000
Credit  Service Fee Revenue                                         22,000.00

 

 

I've determined how to get the Receivable and Revenue accounting (by using a combination of AutoAccounting & Transactions Type defaults), but I can't figure out how to get the Adjustment for Withholding Tax to show up on the AR invoice with the correct accounting.  (This is not Sales Tax)

 

I thought I could use a Standard Memo Line, but I can't figure out what Type to make the Memo Line, nor how to get the distribution line to default the right GL account for Withholding Tax.