You will be making this update on your product page, not on the cart page. Currently you have the productoptionID from the $sizeOptions_rs recordset set as the value of your size select list. To make it work correctly you will need to have another recordset that is almost identical to the current sizeOptions_rs recordset. The only difference is that this second recordset will be filtered on the posted optionID.
Add a new recordset and go to advanced view, in here you will have the query like this:
SELECT * FROM productoptions
You will need to update it to be like this:
SELECT * FROM productoptions
WHERE productoptionID = colname
Then just under the query view in the advanced interface you will add a new query variable, it will have settings like this:
name: colname
type: numeric
default value: -1
runtime value: $_POST['SoftDipesCart1_4_Price_Add']
This should create a new recordset for you that is filtered on the selection of the posted size select list. You can then go into your add to cart server behavior and in the bindings tab select your column and then using the lightning bolt icon select the value that will be coming from this newly defined recordset. This way you can add any details about the selected size in your add to cart server behavior.
