Yes, it is six and then -th. It isn't an easy word to pronounce - which is probably why it appears in tongue twisters, such as "The sixth sick sheik's sixth sheep's sick".

The word "six" ends with an /s/ sound. But this /s/ disappears when you say "sixth". If you try to say it with the /s/ then it will sound strange and be very hard. Also, try saying "sick" - you should hear a clear /k/ sound at the end. But when you say "sixth", don't release the /k/ but move straight to the /θ/ ("th").

Please listen here: http://www.thefreedictionary.com/sixth Click on the icon of the loudspeaker to hear an American man pronounce it. Click on the icon of the American flag to hear an American woman pronounce it, and on the British flag to hear an Englishman pronounce it.

There is no such thing as a "correct pronunciation", unless you are trying to pronounce "sixth" as "SEVENTH". Having said that, here are the world's authorities on English pronunciation; http://www.oxforddictionaries.com/us/definition/american_english/sixth http://dictionary.cambridge.org/us/pronunciation/english/sixth http://www.collinsdictionary.com/dictionary/english/sixth http://www.ldoceonline.com/search/?q=sixth http://www.ldoceonline.com/dictionary/sixth-sense http://www.macmillandictionary.com/us/dictionary/american/sixth https://www.ahdictionary.com/word/search.html?q=sixth&submit.x=40&submit.y=19 http://dictionary.reference.com/browse/sixth?s=t http://www.learnersdictionary.com/definition/sixth http://www.merriam-webster.com/dictionary/sixth which leaves a zero possibility of any misunderstanding. Unless of course you are doing a research project on English dialects or mispronunciations.

"pronounced like normal six then add th sound" = Yes (voiceless th). "So should I pronounce it like this "sikth"?" No. Some natives may have a slight lisp, in which case, yes, it would be "sikth". Or perhaps even "thikth".