See explanation below.
Explanation:
You need to create a sales order then create a proforma invoice for the sales order.
Create the sales order:
* Go to Navigation pane > Modules > Accounts Receivable > Sales orders > All sales orders.
* Select New.
* In the Customer account field, select the drop-down button to open the lookup.
* In the list, find and select the customer record for Contoso Retail Los Angeles.
* Select OK.
* Under the Sales order lines section, select the Sales order line.
* In the Item number field, select the drop-down button to open the lookup.
* Select item T0001.
* If the Size dimension is not displayed, click on Sales order line > Display > Dimensions.
* Select the Size dimension.
* Click OK.
* In the Size field, select the drop-down button to open the lookup.
* Select Size 10.
* In the Quantity field, enter 1.
* Click on the Sell tab.
* Under Generate, select Confirm sales order.
* Click OK.
Create the proforma invoice:
* On the sales order page, click on the Invoice tab.
* Under Generate, select Pro forma invoice.
* Set the Print invoice option to Yes.
* Click OK.
* Click on Export.
* Save the invoice in Microsoft Excel format to the Downloads\Sales folder Reference:
https://docs.microsoft.com/en-us/dynamics365/supply-chain/sales-marketing/tasks/create-sales-orders