What is ample knowledge

have ample or an ample knowledge

What is the best way to write that expression?

I´d like to show that a person has a more than sufficient knowledge about a subject, in a cover letter for executive position

I have an ample knowledge ...
or:
I have ample knowledge ...

Thanks.

PS: If you know a better wording for that purpose, please tell me.
What is the best way to write that expression?

I´d like to show that a person has a more than sufficient knowledge about a subject, in a cover letter for executive position

I have an ample knowledge ...
or:
I have ample knowledge ...

Thanks.

PS: If you know a better wording for that purpose, please tell me.
If it applies, "I have extensive Knowledge. . . " would sound better.
Sandpiperliliy:

I´d like to use it in a cover letter, beggining a sentence like:

I have ample knowledge of XXX (company name) activities ...


PS: previously I tried "... extensive knowledge..." but sounded quite arrogant to me.
Sandpiperliliy, you asked me to write the full sentence, and I did it.
Do you go for "ample" instead of "an ample" then'
Thank you in advance.
If you know a better wording for that purpose, please tell me.
For some reason 'ample' does not usually collocate with 'knowledge', according to searches on BNC and COCA: zero hits for 'ample knowledge' in either corpora. 'Extensive' is on the other hand a quite common collocate. If you don't like it, 'comprehensive' might be an alternative.