Question about shipping charges

I have a small local business and the majority of my customers pick up their order and I do not charge these customers shipping. Is there a way on the form to only charge the flat rate shipping to the customers that select shipping as an option. I am currently adding a multiple choice selection so that they choose local pick up or shipping. I looked at creating a condition for this but I couldn't figure out how to do it. Can you help me? 

You need to create your product list using the basic fields and then calculate them manually using the form calculation widget. That way, you can charge them a shipping fee if they selected the shipping option.

Guide: How-to-Perform-Form-Calculation-Using-a-Widget

Here's a demo form: https://form.jotform.com/201628215709050

The single choice option has assigned calculation values: How-to-Assign-Calculation-Value

Please check and see if that could work for your needs.