The Recharge costs feature lists expenses or bills incurred and allows you to select them to populate a sales invoice in order to recharge them to a customer.
To turn on the Recharge costs feature head to Settings > Configure system > Toggle Features
Then scroll down the page until you see Recharge costs and select the tick box beside it.
Navigate to Sales > Recharge costs and you will see a list of all expenses and costs. Use the filters to find the costs to recharge, select them with the check boxes and then use the Add to invoice button to create the invoice.
Complete the details of the invoice as usual adding any other lines for income. Note that you can select individual lines and re-order them by dragging & dropping. Once happy with the invoice click the Save button.