There is a technique for someone with little strength to incapacitate an opponent at least long enough to start running. This technique is called meiuchi or me uchi in Japanese as seen at the start of this video
You may want to watch the full speed strikes in slow motion to really understand what is happening.
This is a strike to the eyes, but it is not an eye gouge. Instead you slap the eye lids with the back of the fingers at high speed.
The technique is similar to a basic punch, the same movements of any good punching technique will be required. So you start from the feat push through the hips move the shoulders and then throw the hand forward.
However rather than striking though the target you must pull back your arm just as you connect with the target and allow the fingers to continue forward in a whipping action.
When practising with a heavy bag or a hand held pad you don't aim to move the bag or pad with this techinque. Rather you know you have it correct if you make a loud clapping noise with each strike.
This is a non-lethal self defence technique. It is extremely painful, but unlikely to do any serious damage. It creates an opening to escape or set up a grapple. It almost certainly will not do more than this. It won't for example knock someone out.