I ride a mountain bike with front suspension. I've recently seen fork lube for sale on an online retailer. This got me thinking. Do I need to be using fork lube? How does it help? If I bought some how often do I need to use it and how do I apply it?
Consult the repair manual for your fork. It will tell you where to lubricate and how much to apply. Without knowing what fork you have, we can others only speculate. Check the manual or post the model and we can look at it.
I have not looked into this but my first inclination is to avoid it. Your fork already has oil on the inside and seals that are supposed to keep elements on the outside. So, for this lube to make much of a difference it would have to soak into the seals, which means the seals aren't that sealed!
I would also think that putting lube on the stanchions would attact grit and grime, something I work hard at keeping away from them.
If your fork is sticking or otherwise not moving smoothly through it's travel, you may want to look into getting it rebuilt.
Just my two cents.