Question: So we call a French male "Frenchman", an English male "Englishman", and a Dutch male "Dutchman". what do we call Swiss males?

"Swissman" comes to mind, but it sounds like a cheesy version of Superman, like "Cheddarman" or "Mozzarellaman".

Answer: 
A man from Switzerland is called a **Swiss man**. 

You can tag the nouns: male; man/men; gentleman; guy/s; woman/women; girl; boy; baby etc. to any nationality. And rightly so, otherwise phrases like: 

> 
> "He married a Swiss"
> 
> 
> 

and 

> 
> "The other day while travelling into France by train, we talked to a very friendly Swiss"
> 
> 
> 

are needlessly vague or ambiguous.

Moreover, **Swiss man** should not be spelt as one word. Some other examples are an *Italian man*, a *Brazilian man* a *Chinese man*. I tend to spell **English man** as two words but it can be spelt as one word, likewise **Frenchman** and **Frenchwoman** are commonly used names. 

The words Englishman, Englishwoman, Frenchman, Frenchwoman, and Scotsman are [nouns](http://www.edufind.com/english/grammar/nouns6.php) in their own right. 

Even the Swiss news use the term [Swiss man](http://www.thelocal.ch/20130725/prince-georges-website-swiped-by-swiss-man) themselves.

> 
> Prince George's website swiped by Swiss man
> 
> 
>
Whichever the nationality, it is an Adjective in a Noun Phrase, whether you tag on a denominator or gender or other such noun. 

So, "I'm a Swiss (man / woman / citizen / denizen / etc.)" is fine. Or then simply say, "I'm Swiss" leaving out the [indefinite] article. 

(Please do post a comment if you don't agree with me).