To play a skill perk on a soldier follow these steps:

• When you have a skill perk card that can be used, a small red badge will appear on the corner of the soldier info tag. Tap on that soldier.
• Once on the manage soldier screen, if a skill perk can be applied to the soldier, a skill slot will be pulsating with an exclamation mark on it. If you see one, tap it.
• The game will now show you the available skill perk cards that can be applied on that soldier. You can now APPLY the perk.