AntiBot JS option is a part of the Login Guard module (Brute Force Login Protection).
You can use AntiBot JS includes for custom 3rd party form.
There's also "AntiBot Forms" option you may use to enter the selectors of the 3rd party login forms for use with AntiBot JS. The default selectors are:
Note: IDs are prefixed with "#". Classes are prefixed with ".".
IDs are preferred over classes.
Important: This is experimental. Please contact support for further assistance.
If you have some additional registration forms that you'd like the "I am Human" checkboxes to add, the setting that does this is 'Bot Protection' under the Login Guard module.
But this only support standard login/register/password forms on WordPress. If you have custom login forms, you can use the Antibot JS to add the protection also - however, depending on the custom form, it may not make a difference if Shield doesn't support it.
Please note that the AntiBot JS feature is available with Shield Pro only. To find out what the extra features for Shield Pro are, read the article here.