How should I link with "Actors" in the "Story board"?

An actor is an artifact in the RRC project, which can link to almost anything else.

It's not clear whether you are asking (1) or (2):

1. "What cursor or mouse motions do I make to create a link?"

In the sidebar (when the storyboard is open), you can Add a Link to an actor or any other artifact. Alternatively while the actor is open you can create the link from the actor to the storyboard. Last, for either artifact, when the View All Artifacts list is on the screen, you can use the pencil menu to create a link.

2. "What kind of link should I make, and in what circumstances should I make a link?"

I think (2) is a much more interesting question. The short answer is "it depends". Every link you make has a cost:

a person decides to make the link
the person makes the link
RRC server and client take time and resource to get the link and display it in the user interface, reports, etc.
others see the link and perhaps think about why it's there
others follow the link
as the artifacts in the system change (and as your team's understanding of the requirements improve), someone needs to evaluate whether the link is still correct, needed, etc.

None of these costs are significant for a single link. But if you have hundreds or thousands of links, the costs start to become "overhead", and you want to minimize these costs.

So the principle to follow is this:

A. Only make links that will later help you or your teams answer questions or understand a set requirements and related artifacts.

Another is this:

B. Establish a pattern your teams can follow: what types of artifacts should have links (and which kinds of links).

By documenting the pattern your teams should follow, you will reduce their uncertainty and the effort they spend on unnecessary links while at the same time improving the quality of their requirements and the value they get from them.

So let's consider these principles in answering your question framed by (2) above: "What link type should I use between actors and storyboards?"

I am assuming (A): you have decided that this relationship is important to make visible. Using principle (B) the most important thing is to pick one link type and use it consistently for links between actors and storyboards. You can create any link type you want. Make it descriptive, for example, you could do this:

An actor "Participates in" a storyboard
A storyboard "Includes participant" actor

If you don't want to create custom link types, or you want to link across RRC projects (for example, if your actors are in a project area shared by many individual project initiatives in your organization), then use one of the built-in link type, for example:

An actor "Link to" a storyboard
A storyboard "Link From" actor

Or vise versa (whichever direction makes the most sense to you).