Create the chat menu and add “/w gm “ in front of it. Depending on what game you are playing and which character sheet you are using you may be able to use specific roll templates to give it a specific appearance. Edit to add: Token Action buttons can either be on the Collection Tab (and therefore will show up for any token that is selected) or they can be on the Attributes & Abilities tab on an individual Character Sheet page, which means they will only show up on a selected token that is linked to that character sheet. So what you will want to do is take your chat menu, add "/w gm " in front of it, and create an Ability on that character's Attributes & Abilities tab, and make sure that 'Show as Token Action' is selected.