You are also able to customize the size of a continuous concrete footing on the Section & Material tab.
1. In the Section window to the right, select the field to the right of the R1'x3'.
2. A balloon will appear to the left of the field.
3. Input your desired dimensions within this balloon.
4. Select the arrow to the left of the field to view your added dimension.
You can easily change the shape and type of material required by selecting the second arrow from the left.
Hope this helps.
Attachment: Concrete foundation size customization.zip