Roll your own derivations
You may have derivations of your own that you wish to try. Just type, paste, or drag and drop, them into the panel, select your derivation, and click 'Start from selection'. [Often copy-and-paste won't work directly from a Web Page; however, usually drag-and-drop will work!]
You will need to use the correct logical symbols. Here they are
F ∴ F & G ∼ & ∨ ⊃ ≡ ∀ ∃ ∴ (or use the palette to produce them)
And the right syntax (the premises separated by commas and then a 'therefore' followed by the conclusion).
So, a selection needs to have a form similar to this
'a..v' are constants, 'w..z' are variables, and you can use subscripts on the constants, variables, functors, and predicates. So here is an example of more advanced syntax.