I had already attempted the provided solution with no success.
I did, however, eventually find a solution and for the benefit of others I'll post it here.
What I had to do was create a custom skin and modify a couple css styles.
.radr_Default
.radr_clipRegion {
border: solid 1px #626262;
/* I added this line */
background-color:Transparent;
}
.radr_clipRegion
{
width: 100%;
height: 100%;
/* I turned this offed */
/* background: white; */
/* We change the width and height from the code, and then this setting becomes active! */
overflow: hidden;
position: absolute;
}