Hi Zone,
Thanks for the clarification. For the table that you have given, Zmin = 1k and Zmax = 10k. Computing for Rfb and Rcal using the formula on Configuring the Part (page 5) of this application note http://www.analog.com/media/en/technical-documentation/application-notes/AN-1252.pdf
Rfb will be 674.42 and Rcal will be 3.67k.
Could you try to change your Rfb to 680 and your Rcal to 3.7k? By doing this, the range of the unknown impedance that you can measure would be from 1k to 10k. The value of Rfb and Rcal depends on the range of the unknown impedance that you will measure.
Regards,
Mark