If the file is related to the model who’s form is on the page, then the file can and should be a part of the form for that model.
If the file is unrelated to the model who’s form is in the page and/or you want to include a separate form for the file upload, then you can use something like
Well all file uploads from what I have seen are within the main form not below the submit button. I guess I will just use a modal box to do the uploads.
I have a Paperclip file upload going inside my model's form, but not
in a form for itself.
I was approaching this as a form issue. Anyway, you should try
Paperclip if it seems like it might help you. Its really extremely
easy file uploads.