I would actually give you the opposite advice.
If you are certain that you want to pursue the CR1 do not file the I129F.
Due to tne USCIS streamlining policy initiated in October, both petitions would be processed at the same center, they would be approved at the same time, and then the I130 would be retained. The USCIS assumes that the beneficiary will adjust status in the U.S. and not pursue a CR1 - unless you "clearly indicate otherwise", but we are not sure what this means.
The simplest answer to your question is NO, you do not HAVE to file the I129F, it's optional, and if you really only want the CR1, it would be a waste.
QUOTE(JimandSarha @ Mar 4 2007, 10:06 AM)

If you can afford the fees, I recommend you file both ways. Generally the K-3 will be faster and offset some of the process until after you arrive here. The CR-1 will be cleaner on arrival and after.
I did both. Neither has been fast. My K-3 application is almost certainly lost at the CSC. I have an approval notice and I also have an RFE status simulataneouly and nothing done so far can seem to either get the "approved 129F to the NVC nor can I seem to send them any information that will clear the RFE status. The CR-1 application plods on like an oxen.
Jim