Yes, the class in this case is raincheck-load,
however the class must be the same in both the button and the Raincheck click.
But in a Source button inserting in extra CSS classes doesn’t work.
Perhaps in the Custom Attribute of the source button you need to enter a name(?) and the value of the class(raincheck-load) ?
Source doesn’t include anything you might not need by default. If you want / need to use jQuery then you can add this stack. Note: Most third party stacks that need jQuery will generally load this themselves anyway.
Also not sure what you are trying to achieve overall exactly, but you can show and hide things with whats built into Source. Eg create a 1 item grid in a grid plus, and then use the category feature to show/hide the image.
Raincheck works with F6 just by providing a class. I think for it to work with other stacks, these stacks should have the same mechanism, don’t they? Stuart has been tagged. Hopefully he can shed some light on this?
Or maybe @joeworkman ?
I don’t know anything about Raincheck but i would have thought that entering the class name in either the Stack’s CSS box or the custom attribute box would be fine (if the name matches with your Raincheck name). If you can publish a page where it doesn’t work with the Source button then it might be easier to troubleshoot.