Heill Djúpstraumr!

> Thanks for the solution!

You're welcome :) Thanks for trying to solve it!
Kudos to Tim and Arlie too.

> What blocked me from solving part a of rune
> project 1 is that I thought the -R came *only* at
> the end of words. This stopped me from even
> *considering* it being in the midst of a word.

Yes. Usually it only comes at the end of words.
But it does seem to have featured in the verb 'to be'.

ek em
þú est/ert
hann es/eR/er

> I assume this happens *only* when additional
> *endings* come after -R ... right?

I suppose. But I'm not absolutely sure which endings
had R and which didn't. I'll try to find out more
and report back to the list.

Kveðja,
HaukR