The large RF monogram on this coin stands for Republique Francaise, or the French Republic. The modern countries of Vietnam, Laos, and Cambodia were called French Indo China until 1954. The half cent series ran from 1935 to 1940.
These coins were minted in bronze and in zinc. But the zinc coins are very scarce and hardly ever seen. Here are approximate catalog values
BRONZE 1/2 CENT
worn: less than $1 US dollar approximate catalog value
average circulated: $1
well preserved: $3
fully uncirculated: $8
coins dated 1940 are more rare; multiply these numbers by two
ZINC 1/2 CENT
worn: $100 US dollar approximate catalog value
average circulated: $400
well preserved: $600
fully uncirculated: $1000
These are catalog values. They apply only to coins that are free of problems, such as spots, scratches, cleanings, stains, nicks, gouges, and the like. Refer to our Terminology page to properly interpret catalog values.