Using a foil/silver reflection panel will give you the reflection of a foil/silver panel in the eyes.
Eyes exhibit several reflectance properties. Some diffuse reflection and some direct reflection. The direct reflection is what makes them behave like mirrors, reflecting the light sources. More specifically, any light source that is in the 'family of angles' will show up in the eyes as a direct reflection. Now, because the eyes are spherical, their family of angles will be a rather wide area in front of the subject...but limited by how open their eyes are. That's the scientific way of saying what we already know...the eyes will reflect the light sources that are in front of them.
So we can use this to control or predict the catch lights that will show up in the eyes of our subjects. If you put a light source to your left, it will show up on the right side of the subject's eyes (their right, our left). If you make the light source bigger (in relation to the subject) it will create a brighter catch light. So using the open sky, or a reflector that is very close to them, can almost fill the family of angles, making the eyes very bright. Of course, you have to watch for things that will block part of the light that is withing the family of angles, namely your self.
So going back to your silver reflection panel....that may help, in as much as you can use it to fill or partially fill the family of angles. If you just hold it up a few feet away, you'll just get a reflection of it in the eyes.
