I accidentally put the wrong side of foil down how can I fix it?

If you’re able to easily pull/peel up the foil from the surface: Lift the foil off the surface, re-exposing the Leaf and Foil Size layer. If you’re not able to easily pull/peel up the foil from the surface: Using a precision cutting tool like an Exacto knife or razor blade, find an edge of the foil and gently try to pry the foil from the Size. Rubbing Alcohol on a Q-tip may help soften the Size adhesive as a last resort. 

Re-apply Size if needed and apply foil. Remember, foils should be applied shiny side (color) face up. 

When pulling off the foil, some Size and paint may pull off due to the extra strength bonding of the Size medium. If sticky Size comes off or bubbles, patch the missing areas with more Size. If paint lifts, depending on the severity of the paint lift, some touch up paint maybe required. If areas are small: touch-up with paint and reapply Size. If paint needs to be removed and the entire surface repainted: To remove old Size and paint from the surface, use a chip brush dipped in rubbing alcohol to soften the Size adhesive. Next, sand off the Size and paint. Then repaint and reapply Size. Make sure the alcohol residue is completely evaporated and removed from the surface prior to repainting.