How do I know which pattern to use?
The best way is to compare what you have from the radio with what
is available. If there is not enough material or it is too badly
decomposed to identify the pattern, then your best bets are to:
1) find someone with the same set or
2) look at a picture of the radio in one of the popular radio picture/price guide books on the market.
Antique Radio Classified has most of them for sale or you can look for them at your local library. As always one must be careful because in some cases these books picture 'restored' radios with cloth that has been replaced with unoriginal material.
In the case of Philco radios Ron Ramirez' book, Philco Radio 1928-1942, has pictures of most every set ever made during that period.