You can easily switch between several reference databases in the "Reference Database Library" dialog: In order to select another existing reference database for being used in future search-match and restrainting operations, please mark (click on) the corresponding line in the Reference Database Library. Afterwards, press the "Select" button at the bottom of the dialog.
If the selected reference database is a PDF-2 (Release after 2004) or PDF-4 database, the validity of the licence will be checked. Afterwards, the reference database will be marked as selected, indicated by the ">>>" arrow on the left-hand side of the corresponding line.
You can now leave the Reference Database Library by pressing "Quit" and apply the selected reference database in phase identifications and database retrievals.