Dave - Omniscope uses Variables to allow end-users to influence formule via manual manipulation of devices that represent the values to be assumed by each Variable. You can define Variables in your file from:
Data > Formulas > Add/Edit Variable {add Variable} which gives you the option to add both numeric ranges (integer or decimal) and fixed, pre-established value numeric choice lists. Each Variable you define adds a corresponding end-user manipulation device to the Sidebar/Device View display.
Once the Variables are defined in the file, you can then define a formula field that divides the current value of one Variable setting by the current value of the other Variable setting.
If you define variables in DataManager, then Load that data into Omniscope, those variable definitions will be present in Omniscope. You may need to show the variables in the sidebar, though.
If this doesn't work, can you post a demonstration?
Chris - You can reveal the Sidebar on the DataManager workspace:
Toolbars > Right sidebar
Then set which Variables are to be visible from the upper left drop-down on the Sidebar. You can also Edit variables from the Sidebar Tools dropdown (blue spanner)