On the settings tab you will see a "Frequency Limits" group. Here you could set Out 1 < 1000000 and then select the "Use Harmonic" type that you require; "Golden Ratio" is my current favorite. Spooky2 will then find the closest harmonic about 1 Mhz using the golden ratio.
Pages 105-106 of the Oct 9th manual go into these controls in more detail.
To set this up you would typically select a preset on the preset tab, and then programs tab, and then settings tab to make these changes, then on Control tab make sure to check 'allow generator overwrites' and choose the channel. If you want to keep the settings in your own program then have a read of pages 58-62 of the October user manual.
For more details, please check the link: