Manuscript Revision: How to include the response to reviewer comments as an attached file? I have recently received a major revision from a journal. In the manuscript upload portal, I find only one place in the form of a text box where I could include the response to reviewer comments. But there is no place link to upload a document. I am thinking of choosing to include the response file as an attachment as it includes mathematical equations. 

So whether a separate file can be attached to include the response to reviewer comments?
This depends on the editorial management system used by the journal. If they let you attach multiple files, then upload the response to reviewers there (be sure it's clearly labelled as a response to reviewers), and write in the text box "see attached file". If they don't let you attach multiple files, then merge the response to reviewers with the manuscript's PDF, upload that, and write in the text box that you've added the response to reviewers to the manuscript because it contains mathematical equations.