To generate an asset in Photoshop from Craft Sync, add a file format extension to the name of the layer you wish to export. All layer assets are exported at 1x by default. If you wish to export the layer at 2x, add ‘@2x’ to the end of the layer name. For example, Layerfirstname.lastname@example.org.
In Sketch, you can generate both 1x and 2x asset exports by creating 1x and 2x export versions in the export panel.