Creating a radio highlight tape

I don't know if anyone here can help with this, but I thought I'd throw it out there.

I cover a minor league baseball team for my paper, and usually get the opportunity to call four or five innings of a game I'm covering on the radio as the analyst. I've always wanted to get involved with baseball broadcasting on the radio, but I enjoy the newspaper end as well. Now, with the way the business is going I figure having that small radio experience would be a good thing to diversify my talents. I've received a lot of good feedback from radio and baseball people about my insights to the game and how I can paint a picture of what's going on.

That being said, I'd like to make a highlight tape, per se, of what I've done on the radio to send with my resume. What is the best way to go about making a tape of myself? What are people looking to hire broadcasters looking to hear? My sister works for a radio station about 45 minutes from where I live and said she'd be happy to help me make a highlight tape since they have the audio editing equipment at her station. So I know I can get it done in good quality.

Any advice anyone has would be greatly appreciated. Thanks in advance.