Hello, 

i would like too append a little text at the end of every new article such as 

"
use this link to get too our news-overview
"
is always in a new article at the bottom. 
Is there a way too do this? Like a template for new articles or something like this?

You can create an override and hardcode this in /templates/your-template/html/com_k2/default/item.php

All k2 items will be displayed with this text as such.