Use of Available for Salesforce Mobile apps flag in Visualforce Page
newly created the visualforce page and its support in Both Platforms (Salesforce Users and Salesforce1 Classic Users (mobile).
Then Check “Available for Salesforce Mobile apps” flag on Your newly created Visualforce Page. If this flag is Unchecked, the Salesforce1 App should show the default layout instead of the Visualforce page.
To enable a Visualforce page for Salesforce1 please follow the below path:
From Setup -> Develop -> Pages.
Click Edit for the newly created/existing Visualforce page.
Select “Available for Salesforce mobile apps” then click Save.
Please Note: you need to specify a visualforce page version as at least 27.0 or above (on the Version Settings tab), then you can check the box to make the page available (Available for Salesforce mobile apps). Then Finally you can now also add pages to the Mobile setting using below navigation menu.
under Setup -> Administration -> Mobile Administration -> Mobile Navigation.