Hi,
it is actually absolutely acceptable to have many documents in the TMF only as electronic records. The trend in the TMF is actually to go to electronic TMFs and the rule is that if the document is created and signed/approved (when appropriate) electronicaly it could be available only as electronic file. If otherwise you have documents signed on paper (not with electronic signature) or stapted you need to scan them (with some appropriate resolution) and archive them as scaned copies (if required by the sponsor) and in their original format - as a paper.
There is a paper of EMA on this topic as well - here is the link: http://www.ema.europa.eu/docs/en_GB/...C500138893.pdf
Hope this helps,
Vyara