One coil of .009 steel is used for the Chikari and sympathetic strings.
You will need to cut these to length.
6th peg sa chic .009 steel
7th peg high sa chic .009 steel

These gauges differ with various traditions, as does the desired action height. The 7-string style sitar has thicker gages. The 6-string style sitars thinner gages. While most double tumba sitars are strung in the 7-string style and single tumba sitars in the 6-string style, you can change the style of your sitar by re-stringing it with the appropriate number and gage of strings. There are a number of string makers producing a variety of string sets that differ in the quality of the wire, the gauge or thickness of the wire, and the type of metal. If you are trying to decide which to use here are some guidelines. English and German makers tend to use high quality, high carbon steel; they are therefore more expensive than Indian sets. The trade off is that high carbon steel is also more prone to rust in a humid climates. If the wire quality is the same, than thinner gauge wires are easier to bend when playing, than heavier gauges. The trade off is that you lose the lower bass notes with the thinner gage wire. When it comes to the type of metal, brass vs. bronze, it is a matter of taste. Bronze has a warmer sound than brass. The trade off is that bronze is more "stretchy" than brass, so it goes out of tune easier.