Hi Amanda,
Thanks for your Post.
Unfortunately Reckon Accounts cannot handle the commission rates on inventory/other type of items. It’s a limitations of the software.
Depending on how you receive your commission- either via as a credit or a deposit from your supplier; you can do the next step based on that.
You can record the credit manually by creating the credit note and then apply that to the future Bills OR do the General journal entries to affect your Bank Account and any Commission tracking account.
Above are suggestions only and you may want to talk to your Accountant or our Partners to see if any other options are available for you.
Hope this helps.
Thanks.
Dharmesh