Hi,
try using GD Post Images in your archive item instead of GD Output Location for that particular field.
When a custom file field is shown in GD Output Locations with the “Show in what locations-> Details sidebar” there isn’t an option to adjust the output file size.
Edit your archive item and add “GD Post Images” and set the image types field to your custom image field key. Then use the advanced options to choose the size of the image.
You can use the shortcode builder to get the shortcode you need for that: https://wpgeodirectory.com/docs-v2/geodirectory/shortcode-builder/
Once you have it showing up with GD Post Images you can remove the details page sidebar option from “Show in extra output locations”
https://wpgeodirectory.com/docs-v2/places/custom/