I found the arrival records of Mary and Jane; Richard appears to have come over earlier. You'll need an Ancestry.com account to get at this manifest, or you can try to find it on Ellis Island site. The name of the ship is Carmania. It sailed from Cobh, Ireland to New York, arriving on 13 Sep 1925. These two are on page 19 of 92. Don't forget that these manifest pages are split into two images; hit the 'next page' link to see the second page that shows they were coming to join husband/father Richard Richardson who was then living at 1740 Church St., in San Francisco.
With respect to Richard's arrival, there is a single record on Ancestry.com that is a possible match. I cannot access it because I don't have access to Canadian records. I retrieved the record by searching on Richard Richardson, born 1896-1898, arriving 1923-1925. The hit is for "Canada, Ocean Arrivals (Form 30A), 1919-1924." Perhaps someone else can validate whether that match is plausible or not for your Richard Richardson.
I think the reason this family arrived by ship on the East Coast of North America, rather than directly to San Francisco, is that by the 1920s, it was much faster to cross the continent by train that to take a ship through the Panama Canal.