Thanks for the kind words, FCastellanos - appreciate that :)
I think Tabarkus covered it pretty well, but just in case...
Create a weapon called 'Shield Bash', and then click the magnifying glass to the far right, which will open a dialog window with attack and damage details. To find the d14, right-click on the d20, select Custom Dice, and then select the d14. Drag the die over to the attack dice field and left-click to drop it. This should set your action die for that attack to the d14.
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