magazine style end marks

[lkh]

Hi all,

here's a problem I hope someone can help me with:

For a small fanzine project I want to typeset magazine
style end marks [1]. Particularly I want to include the
authors handle or name in the end mark, like seen for 
instance in some articles like in this issue of the
Space Gamer Magazine [2].

So in any case the end mark should be flush right. 
Either on the last line of the article, or - if that
line is to long to accomodate the end mark - on the 
following line.

In LaTeX I think I could get away with an \hfill, but 
from what I understand, flexible horizontal filling 
doesn't seem to be a concept in roff land (I might be
utterly wrong about this).

I've tried this:

.de Au
.ta \n((LLuR
.ad l
        \[em] \fI\\$1\f
.ad b
..

It works, well, sometimes. When the authors name (given
as parameter $1) is to long, it seems to collide with
the right margin, so a newline is introduced. Also 
this construct fails in two column mode and of course
always moves the mark to the following line.

What would be a proper solution?

Thanks in advance!

lkh

[1]: 
https://rwt.io/typography-tips/marks-ends-and-middles-end-marks-sections-and-dead-ends

[2]: https://archive.org/details/SpaceGamer1981-12/page/n33/mode/2up