Well they are considered interchangeable if used properly as an adverb in the first place. Here's a few guidelines (not rules) that I use when choosing the best fitting form:
Examples:
Well, since oft is just a shortened version of often, I suppose you could use it the same as you would with the original word often.
Ex: The mountains oft covered the setting sun.
The term 'radical' is oft seen in science and math.
use it by saying- how can you use the word ebullient in a sentence?
Just use it! Or do you mean, can you use the word beheld in a sentence.
You can use the word feces in a sentence to mean excrement.
How do you use the word decibel in a sentence?What is decibel used for?
The term 'radical' is oft seen in science and math.
Cato the Elder's oft-repeated 'and I think Carthage must be destroyed'.
oft is a poetic word
Oft is not a shortened word. Often is a lengthened word. The original word is oft and the form often did not appear until about a century before Shakespeare's day. They are, of course, the same word and mean the same thing.
He would oft apologize for things that were no fault of his own. The fault line often produced violent earthquakes.
As we entered the clearing, I beheld the oft vaunted glimpse of the Moon bow.
use it by saying- how can you use the word ebullient in a sentence?
loft
Can you use the word concluding in a sentence? Done.
How can you use the word infectious in a sentence
You can use the word Truss in a sentence like this.
Just use it! Or do you mean, can you use the word beheld in a sentence.