I've been looking for a software to get a FITS file and export 1 file for each of the RED, GREEN and BLUE channels. I came across Nebulosity last week, but I can't buy it's licence since I live in Iran... I'll be grateful if you introduce any similar applications...
You can use Raw Therapee, it's free.
Almost every other software have this feature, Photoshop, Coral Paint Shop Pro and much more. just pick one.
In Paint Shop Pro You go to: Image -> Split Channel -> Split to RGB. Simple as that. In photoshop it should be the same.
Edit: Since spliting TIFF format does not help you I suggested an edit to your question.
You may consider FITS Liberator, which is a software developed by NASA and ESA.
It is also free and was built to support a number of astrophoto formats.
It's available here: http://www.spacetelescope.org/projects/fits_liberator/
Should be available for download for your region.
If you want to buy software, I highly suggest PixInsight. It's what I use. Liscensing is based in the EU, so it may still be a challenge for you.