Posting to separate Facebook accounts
1) Go to My Account > Settings > Social Accounts and connect a Facebook account.
2) Once it's connected, head over to Facebook.com and LOGOUT from that Facebook account
3) Go back into Stencil, and go to My Account > Settings > Social Accounts and click Add another Facebook profile/page
Once both accounts are added, you can share to either one of them or any of the Pages they're associated with.