Please note that ResearchGate is not a publisher, you cannot publish an article here. It is a platform for papers published in journals, or to present unpublished texts, data etc. See these instructions how to add published or unpublished reasearch: https://explore.researchgate.net/display/support/How+to+add+research
Given the facts provided by Dr Wolfgang R. Dick , there are no restrictions to the format you publish on RG but it you are submitting to a journal, they will have other specific requirements (eg font, margins, word count).