A reimbursable expense in Xpert-Timer is an expense that is not necessarily linked to a time. But nevertheless those reimbursables belong to a project and need to be billed to the client. Therefore it makes sense to add them to a project. If you also want the timestamps to be calculated in your total project calculation, you need to create a reimbursable of the time period that needs to be billed.
Reimbursable expenses are for example:
You can display your reimbursables in the "Reimbursable ledger". Click on Windows -> Reimbursable ledger. Here you can edit the entries or add new templates for your reimbursables.
When you create a new invoice, those reimbursables will be available for selection.