When Really Simple Barcode starts it dispays a barcode in the centre of its window using the parameters previously saved as defaults:
The type of barcode may be changed by selecting the required barcode type from the drop-down list of type available:
The height of the barcode (which is specified in points just like any other font) may be selected from the drop-down list of font heights, and the width of the barcode may be selected by choosing the required barcode font.
For normal (ie. Non-retail) barcode fonts the selection should be made from the list of
Thinnest Thinner Medium Wider Widest
When creating barcodes for retail packaging (EAN/UCC-13, EAN/UCC-8, UPC-A, UPC-E, ISBN, ISBN-13, etc) then the Short retial or Tall retail fonts may be used.