By default, the program exports cropped images in their original size.
If needed, you can define the size of exported pictures in pixels for any individual preset.
This can be done when you create a new preset using the Crop Setup Panel. Use the Fixed Pixel Export Width option.
Fixed Pixel Export Width - If this field is set to zero, the program exports the crop at the same size it was cut from the photo. If this field is set to a non-zero value, the program resizes the image to the specified width in pixels.
Alternatively, you can manually set this parameter by editing presets as a text file. Below is the line you should edit, along with an example of its usage:
#OutputPixelWidth:<NNN> // Fixed output width (Integer value)
OutputPixelWidth:0 // Export with original size
OutputPixelWidth:1000 // resize image to 1000 pixels