The answer to this will depend on the material your applying it to. Waterproofs typically fall into one of three categories:
Physical waterproof barriers
These are the old style "boil in the bag" type systems where your coated in plastic. This plastic will neither let water in or out. These are rarely used these days.
VLP will have zero affect on these as the barrier is physical and applying things to it makes little difference.
Chemical barrier systems
By this I mean things like Paramo jackets. The waterproofing of these jackets is based on a water repleant chemical coating on the outside of the material.
Adding the VLP to this I would suggest will reduce the water proofing of the the jacket. The whole concept of these jackets is to allow water to run off befoire it becomes a problem. Adding the VLP will prevent this from happening effectivly.
Breathable physical barrier with a chemical coating
by this I mean Goretex, eVent, etc. The water proofing of these jackets is actually provided by the material in the jacket (the GoteText/eVent itself). So adding the vLP to this will have limted effect to the water proofing, it should still keep you dry.
That said the breahtability of these jackets is based on the outer chemical coating and again the VLP is only going to interfere with this. So it will likely prevent the material from working at 100% efficency.
TBH, if you want to be seen, buy a 50p high visibility vest, it will be more effective and won't affect the waterproofness of your clothing in any way shape or form!