Here is the official document published by KTH to do the master thesis.
Basically, to finish a master thesis you also have to be Active listener for at least two master thesis presentation and be once the opponent for any master thesis.
To be the active listener you have to be in the master thesis presentation and you can ask questions.
To be the opponent you have to have the draft at least one week before and send the opponent report (optionally) to the examiner. Then you have to be in the presentation and ask questions.
To prove that you have been as active listener and opositor you need the examiner of the student who has presented to sign a document. As far as I know, there is not official document for whole KTH. In stead, the students can create their own document. What I recommend is use the one provided by Electrical department:
Different departments in KTH have differents rules about the the last day of the presentation of the master thesis in an academic year. For example, for TSLab the last day of the presentation on 2011 is 17th of July, but for Wireless@KTH there is not such deathline. Any student can present her master thesis when there is an agreement with her examiner.
Official KTH web page: http://www.kth.se/ict/internwebb/utbildning/2.14954/examensarbete-1.16410