Suggestions Bubbles in PET Film Installed 2nd Surface

I'm not familiar with PET film, but just about every brand has clear printable vinyl.
When I have to apply clear 2nd surface, I usually do it with 3M clear, wet it
with a baby shampoo and water mixture & don't have many issues with bubbles.

 

After I lay the wet vinyl down, I wet the other side and use a window squeegee to spread the vinyl out,
and then go back and do a hard squeegee.

You're not applying transfer tape are you?

 

Not familiar with PET film, however I do know that when we wet apply clear vinyl or translucent to windows, sometimes it has little bubbles but they will dissipate over time.