Any rules for a suffix on english words?
Since Japanese doesn't have consonant endings (except for 'n', of course)
How do I end the name I'm trying to transcribe? Names like Eric or Robert...
A non-Japanese name that ends in a consonant is transcribed using the -u kanas, and in some cases the -o or the -i. The Japanese language, being moraic, lacks any syllable coda, as you mentioned above. The -u and -i sounds are implicitly silent when they come at the end of a word.
So some examples would be:
Notice with the last one-o is used. In general words ending in "t" use the "to" kana.