In Raley IntakeForms you can set up the rules to concatenate the field values together

This is done by using the the Set Value rule

Here is how this can be configured

You add a rule to react on field change, by expanding field configuration details and clicking on 

Then you define what field you want to update when this field changes, for example:

Here, we set the "description" field with values from our custom "mytextfield" and "priority" field

Similar rule can be added to "priority" field, so when priority changes you see the description field updated as well 

You can also use "set value" rule and calculate values. This is set by just wrapping the expression into the parenthesis ()

For example:

description=(${jif_priority}*10)