They removed long time ago (october/november 2016)
The Kickstart functions no longer work properly due to updates by Microsoft.
We will remove the feature in the next build until Kickstart is needed again to get past screenlocker malware (which is no longer prevalent). Then we will invest into making Kickstart work again on recent versions of Windows.
With HitmanPro, you can set the boot scan function yourself in Settings and this is applicable to your stated operating system W8.1. The HMP scanner is a 30 day free trial only, then it's subscription (pd). There is a PDF near the bottom of the page under "Comprehensive Remediation" that contains more detailed information..
Re: the Kickstart which you inquired about specifically. this does not appear to be compatible with your operating system.
HitmanPro Alert is an anti-exploit software that includes the scanner but without the capability to make any adjustments in the scanner settings. The scanner is for immediate use following a notification from the Alert about a possible exploit but you can use it as an on-demand also.