If you have Advanced Security activated in your account, you will see further options for you to add Security Groups to a record.
In the Action Type List, you will have another option of 'Set sub tab security template'.
Fig 1 Advanced Security Group option
This option allows you to default Security Groups to your records sub tab records. The could be different to the default Security Groups already set up for the header.
Inherit from the header - This option is the default for all records, you do not have to manually set this. If you have previously deviated from the default then you can use this option to go back to inherit the Security Groups from the header.
For all sub entities - If you wish to apply a Security Group different to the Header to all the Sub Tabs, choose this option and select the Security Group from the drop down list.
For individual sub-entities - This option allows you to select a specific Sub Tab option from the drop down list and then specify if this Sub Tab's Security Group be different from the header.
By default all sub tabs inherit from the header, but you can select a specific tab and deviate from the default. The drop down list will allow you to assign an alternative Security Group for that one specific Sub Tab.
For example, you could wish 'Everyone' to see all the header record and sub tabs, but you may wish to lock down the 'Financials' tab to only a 'Finance' security Group.
Note: For more information above Security and sub tab behaviour please read this article https://support.intelligentcontract.com/support/solutions/articles/22000265988-record-and-sub-tabs-behavior-using-security-groups
Once the Sub Tab Security Groups are selected press [Save] the Action will now be added to you Rule.
Multiple Actions
If you wish to trigger multiple Actions for your Rule, click the new button again and add a new Action. You can add as many different Actions as you wish.