RZ was a spirited witness, but ultimately not credible, and her testimony highlighted why eyewitness testimony is often imprecise at best and just plain incorrect at the worst. However, she can play herself in the movie version, with no call to central casting needed.
She said she called and met with the lawyer in the custody hearing and there he was standing right in front of her (Little K) and she didn't recognize him! And then she's describing what this runner looked like who she was positive was Nancy, and there's Nancy's identical twin sister, with hair pulled back in a ponytail, and she doesn't so much as notice the lookalike right in front of her, about 20 ft away. That, combined with her confusion and memory issues does not make her a strong eyewitness.
I'm sure she most definitely did see a female jogger, and I'm sure she did say Hi. But the person she saw that morning wasn't Nancy Cooper.
Now, as for the Food Lion guy who claimed to see Nancy between 6:55am and 7:10am on Kildare...that location is about 2 miles from the Cooper house. If Nancy left her house at 7am, it would have taken her 20 - 25 min to get to that spot. It wasn't her.