Basic question on stacking and aligning

[MikeP]

I have some subs of M33 taken last night through the L filter of my LRGB set (10 by 10 minutes). Fluffy things permitting, tonight I intend to try to get some more subs through the R,G and B filters.

It has been suggested that having captured the L data unbinned, it is sufficient and obviously quicker to bin the RGB data. If I do that, how do I align and stack all the data since the images will be different sizes?

I used Maxim DL 5 for capture and guiding and intended to use it for alignment and stacking.

Mike