As you scan, the "Counted" field of the selected counting journal is updated in D365 FO. To finish the current counting journal, on the Rental counting main page, click "F1:Back". As a result, the warehouse and counting journal selection page is shown. 

When you finish a counting journal in Anywhere for Rental, the counting journal is updated in D365 FO. 

You can start item counting for another counting journal.