I just got 2 new holsters from kt mech. One for a g34 with light that works great. The other is an Owb for a g43 and I think it needs a little more retention.   So I was thinking could I just heat up the kydex with a hair dryer or heat gun then push in around the trigger guard a little or does the retention come from a different spot than the trigger guard on kydex holsters?  Or is there a better solution?
  The holsters seam to be good quality. Not as nicely finished as my comp tac or raven holsters but they where cheaper so...
Thanks for your time!

No retention screw?
http://www.tacticalgear.be/proshop/image/cache/data/DSC_0972-500x500.jpg

No. It's not the mechanized version. Just their standard owb pancake. Gunfighter I think it's called.

You got the right idea, heat with a blower and press in a little.
Dont over do it.