Active signal generator IC for 100kHz
The AD9850 is used in a few complete boards that are readily available from online auction sites. Datahseet to the chip: http://www.analog.com/media/en/technical-documentation/data-sheets/AD9850.pdf

Example of a complete module with passive filters to generate a Sine Wave:


Failing that you could try making your own using a microcontroller generating a pwm according to a sine lookup table.