You can do that by using the virtual key code feature and set a program to press and release multiple keys.
Please refer to the procedure below as it explains the procedure to click "Windows+Ctrl+F".
The virtual key codes of each one of these buttons are as follows:
・"Windows(left)" key ＝「0x5b」
・"Ctrl" key ＝「0x11」
・"F" key ＝「0x46」
1.Select a "Device Automation" ("Desktop Automation") step and click the "Edit..." button next to "Workflow".
2.Add a "Press key" step.
3.Select "Calculated Key" in the drop-down menu of "Key".
4.In "Key code", enter the virtual key code "v0x5b v0x11 v0x46 v0x5b,fu v0x11,fu v0x46,fu".
(※)It is important to separate each key code with a half-width space. Enter "v" before a key code to press it, and ",fu" to release it.
■Using a variable and virtual key codes
You can set the "Key Code" area if you set the virtual key codes to a variable.
Please refer to the attached file (仮想キーコード一覧.pdf) for a list of virtual key codes.