I have 2 sets of images that were taken with different sizes. So one set is 1304 x 976 whereas the other is 1024 x 976. When I attempt to stack these Siril complains. Is there a way around this in Siril itself? Or is my only resort to import the stacked images of each set into Gimp as layers and stack them there?
It is impossible to stack images with different sizes.
So you need to register them before (then cropping the sequence)
Hi Richard,
In my simple brain I thought siril would stack them but I would end up with an image similar to what you get when some of the images have rotated or are misaligned 
Is there an FAQ page that explains how to do this register & crop sequence please?
Stacking is just stacking. Rotation and alignment is done during the registration stage.