Radio button script to insert script in text field if 'yes' radio button selected.

I'm building a form with a text field for which I'd like to give end users the option to bullet the text they've entered.

While ES4 allows captions to be bulletted, end users don't have that option even if the field format is rich text. I discovered a work around using the script below for the text field's exit action.

//value of the field to insert "• " in each line
var sFldValue = this.rawValue;
//you split text in field for each '\r' = newLines made with enter
var tmpFldArray = sFldValue.split("\r");
//tmp string you concat your out text in
var sOutStr = "";

//for each line of text insert '• ' in beginning
for(var i = 0; i < tmpFldArray.length; i++){

//need to add '\r' because split removed it
sOutStr += "• " + tmpFldArray[i] + "\r";
}

//return manipulated string to your field
this.rawValue = sOutStr;

Issues I'd like to fix about this script:

1. A new set of bullets are inserted upon each exit
2. Lines aren't indented.

The end user may not want their entered text to be bulletted so I'd like to have radio buttons that will insert the above script into the text field's exit action if yes is selected and remove it if no is selected.