Our system does support this feature.
In the rent roll the rent will be shown as late on the 6th of the month and we provide late charge billing.
Note: Please notice the link Charge Fee
This late charge pop up appears when you click the link, and will post a late charge to the property journal. This charge will show on both the tenant journal and the tenant statement.
Click on the Charge fee "link"
After processing this form the result is an accounting post to accounts receivable. ( see this on row 3 below) Note: Since there is no affect to the bank, you will see no record.
To post the real payment (as seen on row 4 below), you must use the property journal post-payment, select button ( you have recognized the revenue) Note: Now that you post the late charge payment the record is visible.
Late fees are a bit tricky since the law in your state may not allow this charge. You might be able to charge the fee, but not collect it.