If you're interested in the "Scan to View" barcode feature, but you created a customized packing slip template before the "Scan to View" feature was released, you'll have to manually add some HTML from the default packing slip template to bring it up to date.
*Please note that you must be on a Silver or above plan to customize packing slip templates.
Click Settings (the Wrench icon in the upper right).
Next, select Templates and then Packing Slips from the sidebar on the left.
Find the packing slip that needs the "Scan to View" barcode, and click Edit.
Once the HTML editor appears, click on the section that needs the barcode (probably the Packing Slip Footer) and add the following code (to the very bottom, if you want to match our default location):
<p align="center"><barcode size="small">[Barcode]</barcode></p>
Here's an example of what this code might look like in your packing slip:
Of course, you can adjust the paragraph alignment, remove the paragraph code altogether, adjust the barcode size, or put the barcode wherever your template layout will allow!
And if you're interested in other barcode sizes, try these out: