I see on some sites that "candidate" is used as a verb.
I am candidating for this position.
Can this word be used as a verb?
Yes, the noun candidate can be used as a verb. Verbing nouns is very common in English. However, in a very formal setting such as a job application, I would avoid it. Instead, I'd suggest the following solution:
"I am applying for the position of blah, blah, blah"
The OED lists this as
candidate, v. 2
To stand as a candidate.
- 1848 J. R. Lowell Biglow Papers 1st ser. viii. 122 The can'idatin' line, you know, 'ould suit me to a T... So I'll set up ez can'idate fer any kin' o' office.
- 1884 Cent. Mag. June 308/1 Let him put the question to some [choir-singers] who every spring have to candidate for a situation.
- 1909 Springfield (Mass.) Weekly Republican 2 Sept. 14 Mr. Seccombe candidated in the Goschen church last spring.
Not being in the U.S. myself, I'd look at you oddly if you said you were "canditating for this position".
While there is a tradition of "verbification", it's not advised to coin a new verb yourself in formal speech, especially if an appropriate verb -- in your case applying -- is available. Unmoderated verbing weirds language.
verb (used without object) can·di·dat·ed, can·di·dat·ing.
to become a candidate for service as a new minister of a church; preach before a congregation that is seeking a new minister.
As a BE speaker, novel verbing of a noun makes the speaker sound like they are speaking AmE. If it's common to create new terms, it's in American English rather than British English. I guess what I am saying is it's probably more acceptable to citizens of the US than to those of the UK. In the UK many of them grate and most such usages should be avoided. There are some examples in BE (for instance abusing the name of a maker of vaccum cleaners, most BE speakers would not find 'hoovering' at all out of place, whereas the verbing of 'medal' as in 'Usaine Bolt is medalling' is something only a few sports commentators use in BE) but fewer than AmE.