I tend to build a franken holster because I prefer the single leg strap that Safarliand builds. I take this:
and then mount the holster I want to it. For the HK45Compact, if you're using a light (and by light I mean a full sized light like an X300U), you can probably get away with searching for the full size HK45 in the holster finder. You'll come up with the 6280 SLS like this:
Model 6280 SLS Mid-Ride Level II Retention? Duty Holster - The Safariland Group
Remove the holster from the mid-ride belt loop and mount it to the DFA.
I do similarly, but I use the quick locking system